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There now follows a large brain dump concerning knot theory...
At one time, it was briefly theorised that maybe the ~105 elements of
the periodic table were each a little tangle of energy, and different
kinds of tangling gave rise to different chemical properties. This
sparked a great deal of interest in knot theory. Later this idea was
abandoned, and knot theory became unpopular again. But some people still
study it.
(With String Theory, the idea seems to be coming back somewhat. But I
digress...)
So what actually *is* knot theory? Well, it's the study of mathematical
"knots". As you might expect, these abstract entities have properties
similar to but not quite the same as a real knot in a piece of string.
Fundamentally, a "knot" is a *closed loop* of infinitely bendy, stretchy
string. Notice that if you have the free ends of a piece of string, you
can (in principle) always untangle it given sufficient patience. A
mathematical knot has not free ends, and hence cannot be untangled.
That's what makes it a well-defined entity that you can sit down and study.
Two tangled up bits of this hypothetical string are considered "the
same" if you can turn one tangle into the other without cutting the
string or allowing it to pass through itself. (Shrinking parts of the
knot down to 0 size to make them dissappear is also cheating.)
It is a basic result of knot theory that it's often insanely hard to
determine whether or not two given knots are actually the same or not.
The simplest knot is just a circle. This is called the "trivial knot" or
"unknot", since it's completely untangled. Notice that if you take an
elastic band, you can tangle it up really good without actually cutting
it; this is *still* considered isomorphic to the trivial knot. The next
up is the trefoil knot. Again, this can have several appearences,
depending on how you arrange it.
It is useful to think of "the knot", which is an invariant, unchanging
thing, and "projections" of the knot. A knot projection is basically a
2D drawing of a particular configuration of the knot. Any given knot has
an infinite number of possible projections, ranging from the simple to
the utterly convoluted.
Aside from stretching and shrinking the string, a knot projection can be
"changed" in three fundamental ways. These ways are named after a
mathematician who's name is beyond my ability to spell or pronounce.
Remember we're talking about knot projections, that is, 2D drawings of a
particular configuration of a knot.
- A type I move involves taking a strand, making a small loop with it,
and poking it over the top of another strand. (Or, alternatively, under
it.) This makes the projection slightly more complicated (there are now
more crossings), but does not alter the knot itself. The reverse
process, i.e., drawing a loop back over (or under) a strand, simplifies
the projection. (Note that a loop *around* a strand cannot be
so-simplified. Only a loop completely over or completely under.)
- A type II move involves taking a straight strand and twisting it to
form a loop. You have now added one new crossing to the projection.
Alternatively, untwisting the strand to eliminate a loop, thus reducing
the number of crossings. (You can only do this if nothing passes through
the loop, of course.)
- A type III move involves moving a strand from one side of an unrelated
crossing to the other.
These three moves, then, alter the 2D projection of a knot without
actually changing its fundamental structure --- i.e., which knot it is.
One of the ways to attempt to classify knots is by the construction of
"knot invariants". A knot invariant is basically something you can
compute from the projection of a knot, and which is the same for *all*
possible projections of a given knot.
An immediate consequence of this is that if two projections yield
different values for a given invariant, they are provably *not* the same
knot. (However, if they yield the same value, this does not prove that
they *are* the same; that would be too easy. It is however a desirable
property that it should be "unlikely" for different knots to yield the
same value.)
The way to construct an invariant, of course, is to prove that all of
the three moves listed above leave the invariant unchanged.
The details of specific invariants escape me now. Suffice it to say that
several mathematicians have come up with polynomials that can be
constructed from a knot projection. The polynomial itself doesn't
calculate anything interesting, but its formula is derived from the knot
projection. The algebraic properties of polynomials are used in such a
way that the three moves change the subterms, but when you simplify it
all into standard polynomial form, you get the same answer.
I remember one of these polynomials involves recursively splitting the
knot projection into simpler ones, eventually building a trivial
polynomial for each part, and then combining these polynomials back
together according to how the original parts where connected. Shift some
algebra, and at the end every projection of a given knot comes up with
the exact same polynomial.
There are invariants which are *not* polynomials. It's simply that most
of the popular invariants happen to be polynomials.
Invariants are a nice way to compare knot projections in an attempt to
see if they are different. But how to *describe* a knot unambiguously?
Well, several methods have been put forward.
One rather entertaining way goes something like this. (I've probably
screwed up the algorithm; this is from memory.)
- Pick a starting point on the string, and draw an arrow representing a
direction. Doesn't matter what you pick, but stick to it.
- Trace your way around the knot. Each time you reach a crossing, number
it, starting from 1. If the strand you're on goes over the top, use a
positive number. If it goes under, assign a negative number.
- Write down a list of all the pairs of numbers at each crossing.
- Throw away the lowest number in each pair (ignoring sign).
It is possible to completely reconstruct the know from the list you're
left with. As an example, I just tried a figure of eight knot. From
this, I get the list
-1, +4
+2, -7
-3, +6
-5, +8
Throwing away half the numbers, we get +4, -7, +6, +8, in that order.
To reconstruct the knot, we need to fill in the table:
??, +4
??, -7
??, +6
??, +8
Since the *first* column is always in ascending order, and each pair
always contains one + and one -, we can reconstruct quite easily. Once
we have the two-column table, you can imagine taking some bendy plastic
tubing with some crossings taped together and connecting the crossings
in ascending order to reproduce the knot. (1 is connected to 2, 2 is
connected to 3...)
This method, of course, just describes a specific projection of a knot.
There are many ways to project the same knot, and hence many possible
sequences of number to describe it. (Changing the starting point also
alters all the numbers.)
An alternative way to describe knots is by "braid theory".
A "braid" is a series of vertical strands. Initially, they are all
parallel. If you say "+3", that means that strand 3 and strand 4 swap
places, with strand 3 going over the top of strand 4. Alternatively,
"-3" means the same swap, but strand 4 going over the top.
In this way, you can say "-3, +5, +2". This describes a sequence of
strand swaps, starting from the top and working downwards. Something
like this:
1 2 3 4 5 6
| | | | | |
| | \ / | |
| | / | |
| | / \ | |
| | | | | |
| | | | \ /
| | | | \
| | | | / \
| | | | | |
| \ / | | |
| \ | | |
| / \ | | |
| | | | | |
1 2 3 4 5 6
So that's a braid. Now if you imagine taking this and bending it over so
that the ends at the top connect with the ends at the bottom, this would
make a closed loop. In fact, in this case, the result would be *several*
closed loops. The 1 strand would be an unknot, not connected to anything
else. Strands 5 and 6 would become a single strand, which can then be
untwizzled to make an unknot. And strands 2, 3 and 4 would be connected;
off the top of my head, I'm not sure if this would be a nontrivial knot.
Such a collection of possibly-connected knots is called a "link". In
general, "closing" a braid (i.e., connecting its ends together) produces
a link. Sometimes the whole link consists of one knot (i.e., one
continuous strand), and sometimes several knots that can be seperated.
And occasionally, several knots connected such that you can't seperate
them without cutting.
The fun part, of course, is the algebraic structure of a braid.
Sometimes when you move a twist up or down the sequence, it changes the
resulting link when the braid is closed. And sometimes it doesn't.
Teasing how the relationships for this can get quite interesting.
Best of all: any possible knot or link can be represented as a braid.
(Although working out how usually isn't easy.)
Another method for constructing knots is to use "tangles".
A "tangle" is a section of string or strings that have 4 ends. The ends
are locked in place and can't move, and you can't loop the strands over
those ends. If you imagine drawing a square with one end bolted to each
corner of the square and the strands inside not allowed to leav the
confines of the square, that's roughly what a tangle is.
Again we have an algebra of tangle construction here. (I may well be
getting some lefts/rights mixed up here, but the ideas are essentially
correct.)
We start with the "0 tangle". This is where the two top corners are
linked, and the two bottom corners are linked, and the strands aren't
tangled up in any way.
Then we have the "1 tangle". This is where you take the 0 tangle and
swap round the two right ends, such that the strand from the bottom-left
corner passes over the one from the top-left corner. The "-1 tangle" is
identical, but twisted the opposite way. (I.e., the top-left thread is
on top.)
You can "add" two tangles together by placing them side by side, and
connecting the two right-hand ends of the left tangle to the two
left-hand ends of the right tangle.
If, for example, you add a 0 tangle to a 0 tangle, you get a new 0
tangle. If you add a 1 tangle to a -1 tangle, you also get... a tangle
where one thread moves over the other, and then back again. Performing a
type-I move, this becomes the 0 tangle again.
So, 0 + 0 = 0 and (+1) + (-1) = 0. That's cute. But if you add a 1
tangle to a 2 tangle, you get a tangle where the two threads cross over
each other twice in the same direction - the "2 tangle". (A "-2 tangle"
is defined similarly, but with the twist in the opposite direction.)
So, an N tangle is the 0 tangle twisted N times clockwise, and a -N
tangle is twisted N times anticlockwise. (Assuming you look at it from
the right direction.)
There is also an "infinity tangle", which is like the 0 tangle, rotated
90°. And, as well as "adding" tangles, you can also "multiply" them.
This involves placing one above the over, and joining the corners in
that direction instead.
Here, however, we find that tangle algebra doesn't work *quite* like
number arithmetic; if you multiply the 0 tangle by the 0 tangle, you get
something that isn't even a tangle; it's like a 0 tangle with a trivial
knot floating in the middle of it. And a 1 tangle multiplied by a 1
tangle gives you something that can't be described any other way. (In
particular, *not* a 1 tangle!)
By pairing up the ends of a tangle (either vertically or horizontally -
it makes a difference) you can again construct any possible knot. And
again there's an interesting algebra of operations which are equivilent
and those which are not.
In a similar way, you can "add" regular knots. You take two knots, cut
them both, and join the cut parts. The thing is, depending on exactly
where you cut them, and how you join the ends up, you can make several
different knots in any addition operation. So for general knots,
"adding" isn't very precisely defined. (At least, if you just specify
two knots and that they be added, the result is not well-defined. You
need to specify lots of extra info to make it well-defined. Even the
knot projection might make a difference.)
There are other ways of making knots too. The trefoil is a "toriodal
knot". That is, you can generate it by marking a point on a circle, and
rotating that circle while sweeping it around a perpendicular circle.
(In other words, tracing a path on the surface of a torus.) By varying
the number of rotations of one circle for each rotation of the other,
you can build various different knots, of which the trefoil is just one.
(There is an infinite set of parameters that generate any given toriodal
knot, however.)
Related to this are "cable knots". This involves sweeping a circle not
along a circle but along another knot. Sometimes the result can be
unravelled to be isomorphic to the original knot; sometimes it can't.
(In other words, sometimes it's a genuinely new knot.) You can also
generate links this way by not rotating the circle as it is swept;
sometimes these links are seperable, and sometimes they aren't.
What about knots in 4D instead of just 3D? What would that be like?
Well, it turns out to be pretty boring, actually. In 4D, and knot
composed of a 1D strand can actually be completely untangled. That is,
every knot is equivilent to the trivial knot in 4D. That's not terribly
interesting.
What you *can* do, however, is construct knots out of a 2D "ribbon"
rather than a 1D "string". The result is a family of knots that only
exist in 4D, but it's really *far* too mind-bending to think about.
(Projecting back into 3D can look pretty though...)
While we're on the subject of pretty pictures, there is various software
to perform "knot relaxation". The idea is to take a description of a
knot, and try to "simplify" it by treating the knot as being made out of
bendy, stretchy plastic and doing a small physical simulation. An
intricately tangled length of string is likely to untangle itself given
sufficient energy to escape any local minima and assume a low-energy
final state.
It can be quite interesting to watch, and it's sometimes a useful way to
figure out if two knots are the same. If they are, they typically tend
to assume similar final configurations. (But not always...)
This has been another broadcast brought to you by an under-employed
computer science graduate, for the benefit of similarly over-interested
souls. TTFN!
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Invisible wrote:
> There now follows a large brain dump concerning knot theory...
...and now to check Wikipedia and find out whether all that stuff I just
wrote is even remotely correct! :-D
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> There now follows a large brain dump concerning knot theory...
An interesting read, are there any real world applications currently? If I
knit myself a jumper and then join the two lose ends together, what sort of
know is that? Haha only joking.
OOC did you ever consider doing a PhD in some subject you are interested in?
I get the impression you would really enjoy it and maybe you can do it in
parallel with your current job.
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>> There now follows a large brain dump concerning knot theory...
>
> An interesting read
Thank you. I read that while I was a bored teenager.
[Insert comment here about what a bored teenager *should* be doing.]
My memory is a little rusty by now... o_O
> are there any real world applications currently?
Apparently DNA tends to get tangled and knotted, and there's protein
folding. These are both loosely related to knot relaxation. But
hard-core knot theory itself? No, not a huge number of directly
practical applications.
The subject *is*, however, ripe with humour.
"What's your favourit branch of mathematics?"
"Knot theory."
"Me neither."
> If I knit myself a jumper and then join the two lose ends together, what
> sort of knot is that? Haha only joking.
Smart-arse. :-P
> OOC did you ever consider doing a PhD in some subject you are interested
> in? I get the impression you would really enjoy it and maybe you can do
> it in parallel with your current job.
1. I barely passed my BSc. Studying something even harder would seem unwise.
2. AFAIK, you need an MSc before you can even attempt a PhD. Since I
nearly failed a BSc and an MSc is significantly harder, it seems
unlikely that I could get this. (To say nothing of the minor detail of
it requiring tens of thousands of pounds in course fees and several
years of my time.)
3. I severely doubt that I could actually perform a PhD at the same time
as doing a full-time job.
4. I already have a BSc, and it hasn't opened any doors for me. I
seriously doubt a PhD would be any significant help in this direction.
I could continue, but I think that'll do for now.
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Invisible wrote:
> At one time, it was briefly theorised that maybe the ~105 elements of
> the periodic table were each a little tangle of energy, and different
> kinds of tangling gave rise to different chemical properties. This
> sparked a great deal of interest in knot theory. Later this idea was
> abandoned, and knot theory became unpopular again. But some people still
> study it.
Correct:
http://en.wikipedia.org/wiki/History_of_knot_theory
> It is useful to think of "the knot", which is an invariant, unchanging
> thing, and "projections" of the knot.
Wikipedia claims these are "knot diagrams".
> Aside from stretching and shrinking the string, a knot projection can be
> "changed" in three fundamental ways. These ways are named after a
> mathematician who's name is beyond my ability to spell or pronounce.
> Remember we're talking about knot projections, that is, 2D drawings of a
> particular configuration of a knot.
>
> - A type I move involves taking a strand, making a small loop with it,
> and poking it over the top of another strand. (Or, alternatively, under
> it.) This makes the projection slightly more complicated (there are now
> more crossings), but does not alter the knot itself. The reverse
> process, i.e., drawing a loop back over (or under) a strand, simplifies
> the projection. (Note that a loop *around* a strand cannot be
> so-simplified. Only a loop completely over or completely under.)
>
> - A type II move involves taking a straight strand and twisting it to
> form a loop. You have now added one new crossing to the projection.
> Alternatively, untwisting the strand to eliminate a loop, thus reducing
> the number of crossings. (You can only do this if nothing passes through
> the loop, of course.)
>
> - A type III move involves moving a strand from one side of an unrelated
> crossing to the other.
>
> These three moves, then, alter the 2D projection of a knot without
> actually changing its fundamental structure --- i.e., which knot it is.
Wrong:
http://en.wikipedia.org/wiki/Reidemeister_move
> The details of specific invariants escape me now. Suffice it to say that
> several mathematicians have come up with polynomials that can be
> constructed from a knot projection. The polynomial itself doesn't
> calculate anything interesting, but its formula is derived from the knot
> projection. The algebraic properties of polynomials are used in such a
> way that the three moves change the subterms, but when you simplify it
> all into standard polynomial form, you get the same answer.
>
> I remember one of these polynomials involves recursively splitting the
> knot projection into simpler ones, eventually building a trivial
> polynomial for each part, and then combining these polynomials back
> together according to how the original parts where connected. Shift some
> algebra, and at the end every projection of a given knot comes up with
> the exact same polynomial.
Wrong:
http://en.wikipedia.org/wiki/Alexander_polynomial
http://en.wikipedia.org/wiki/Jones_polynomial
http://en.wikipedia.org/wiki/Alexander-Conway_polynomial
http://en.wikipedia.org/wiki/HOMFLY_polynomial
> One rather entertaining way goes something like this. (I've probably
> screwed up the algorithm; this is from memory.)
>
> - Pick a starting point on the string, and draw an arrow representing a
> direction. Doesn't matter what you pick, but stick to it.
>
> - Trace your way around the knot. Each time you reach a crossing, number
> it, starting from 1. If the strand you're on goes over the top, use a
> positive number. If it goes under, assign a negative number.
>
> - Write down a list of all the pairs of numbers at each crossing.
>
> - Throw away the lowest number in each pair (ignoring sign).
>
> It is possible to completely reconstruct the know from the list you're
> left with.
Wrong:
http://en.wikipedia.org/wiki/Dowker_notation
(Note particularly that my algorithm is wrong, and that the notation is
ambiguous in a precise way.)
> An alternative way to describe knots is by "braid theory".
>
> A "braid" is a series of vertical strands. Initially, they are all
> parallel. If you say "+3", that means that strand 3 and strand 4 swap
> places, with strand 3 going over the top of strand 4. Alternatively,
> "-3" means the same swap, but strand 4 going over the top.
>
> In this way, you can say "-3, +5, +2". This describes a sequence of
> strand swaps, starting from the top and working downwards. Something
> like this:
>
> 1 2 3 4 5 6
> | | | | | |
> | | \ / | |
> | | / | |
> | | / \ | |
> | | | | | |
> | | | | \ /
> | | | | \
> | | | | / \
> | | | | | |
> | \ / | | |
> | \ | | |
> | / \ | | |
> | | | | | |
> 1 2 3 4 5 6
>
> So that's a braid. Now if you imagine taking this and bending it over so
> that the ends at the top connect with the ends at the bottom, this would
> make a closed loop. In fact, in this case, the result would be *several*
> closed loops. The 1 strand would be an unknot, not connected to anything
> else. Strands 5 and 6 would become a single strand, which can then be
> untwizzled to make an unknot. And strands 2, 3 and 4 would be connected;
> off the top of my head, I'm not sure if this would be a nontrivial knot.
>
> Such a collection of possibly-connected knots is called a "link". In
> general, "closing" a braid (i.e., connecting its ends together) produces
> a link. Sometimes the whole link consists of one knot (i.e., one
> continuous strand), and sometimes several knots that can be seperated.
> And occasionally, several knots connected such that you can't seperate
> them without cutting.
>
> The fun part, of course, is the algebraic structure of a braid.
> Sometimes when you move a twist up or down the sequence, it changes the
> resulting link when the braid is closed. And sometimes it doesn't.
> Teasing how the relationships for this can get quite interesting.
>
> Best of all: any possible knot or link can be represented as a braid.
> (Although working out how usually isn't easy.)
Wrong:
http://en.wikipedia.org/wiki/Braid_theory
> Another method for constructing knots is to use "tangles".
>
> A "tangle" is a section of string or strings that have 4 ends. The ends
> are locked in place and can't move, and you can't loop the strands over
> those ends. If you imagine drawing a square with one end bolted to each
> corner of the square and the strands inside not allowed to leav the
> confines of the square, that's roughly what a tangle is.
>
> Again we have an algebra of tangle construction here. (I may well be
> getting some lefts/rights mixed up here, but the ideas are essentially
> correct.)
>
> We start with the "0 tangle". This is where the two top corners are
> linked, and the two bottom corners are linked, and the strands aren't
> tangled up in any way.
>
> Then we have the "1 tangle". This is where you take the 0 tangle and
> swap round the two right ends, such that the strand from the bottom-left
> corner passes over the one from the top-left corner. The "-1 tangle" is
> identical, but twisted the opposite way. (I.e., the top-left thread is
> on top.)
>
> You can "add" two tangles together by placing them side by side, and
> connecting the two right-hand ends of the left tangle to the two
> left-hand ends of the right tangle.
>
> If, for example, you add a 0 tangle to a 0 tangle, you get a new 0
> tangle. If you add a 1 tangle to a -1 tangle, you also get... a tangle
> where one thread moves over the other, and then back again. Performing a
> type-I move, this becomes the 0 tangle again.
>
> So, 0 + 0 = 0 and (+1) + (-1) = 0. That's cute. But if you add a 1
> tangle to a 2 tangle, you get a tangle where the two threads cross over
> each other twice in the same direction - the "2 tangle". (A "-2 tangle"
> is defined similarly, but with the twist in the opposite direction.)
>
> So, an N tangle is the 0 tangle twisted N times clockwise, and a -N
> tangle is twisted N times anticlockwise. (Assuming you look at it from
> the right direction.)
>
> There is also an "infinity tangle", which is like the 0 tangle, rotated
> 90°. And, as well as "adding" tangles, you can also "multiply" them.
> This involves placing one above the over, and joining the corners in
> that direction instead.
>
> Here, however, we find that tangle algebra doesn't work *quite* like
> number arithmetic; if you multiply the 0 tangle by the 0 tangle, you get
> something that isn't even a tangle; it's like a 0 tangle with a trivial
> knot floating in the middle of it. And a 1 tangle multiplied by a 1
> tangle gives you something that can't be described any other way. (In
> particular, *not* a 1 tangle!)
>
> By pairing up the ends of a tangle (either vertically or horizontally -
> it makes a difference) you can again construct any possible knot. And
> again there's an interesting algebra of operations which are equivilent
> and those which are not.
Wrong:
http://en.wikipedia.org/wiki/Tangle_theory
> In a similar way, you can "add" regular knots. You take two knots, cut
> them both, and join the cut parts. The thing is, depending on exactly
> where you cut them, and how you join the ends up, you can make several
> different knots in any addition operation. So for general knots,
> "adding" isn't very precisely defined. (At least, if you just specify
> two knots and that they be added, the result is not well-defined. You
> need to specify lots of extra info to make it well-defined. Even the
> knot projection might make a difference.)
Wrong:
http://en.wikipedia.org/wiki/Knot_sum
(There are only two possible results from a knot sum, and it doesn't
matter where the join is, only the relative orientation of the two knots.)
> There are other ways of making knots too. The trefoil is a "toriodal
> knot". That is, you can generate it by marking a point on a circle, and
> rotating that circle while sweeping it around a perpendicular circle.
> (In other words, tracing a path on the surface of a torus.) By varying
> the number of rotations of one circle for each rotation of the other,
> you can build various different knots, of which the trefoil is just one.
> (There is an infinite set of parameters that generate any given toriodal
> knot, however.)
Correct:
http://en.wikipedia.org/wiki/Torus_knot
> Related to this are "cable knots". This involves sweeping a circle not
> along a circle but along another knot. Sometimes the result can be
> unravelled to be isomorphic to the original knot; sometimes it can't.
> (In other words, sometimes it's a genuinely new knot.) You can also
> generate links this way by not rotating the circle as it is swept;
> sometimes these links are seperable, and sometimes they aren't.
Wrong:
http://en.wikipedia.org/wiki/Cable_knot
http://en.wikipedia.org/wiki/Satellite_knot
> What about knots in 4D instead of just 3D? What would that be like?
>
> Well, it turns out to be pretty boring, actually. In 4D, and knot
> composed of a 1D strand can actually be completely untangled. That is,
> every knot is equivilent to the trivial knot in 4D. That's not terribly
> interesting.
>
> What you *can* do, however, is construct knots out of a 2D "ribbon"
> rather than a 1D "string". The result is a family of knots that only
> exist in 4D, but it's really *far* too mind-bending to think about.
> (Projecting back into 3D can look pretty though...)
Correct:
http://en.wikipedia.org/wiki/Knot_theory#Higher_dimensions
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> 1. I barely passed my BSc. Studying something even harder would seem
> unwise.
But let me guess, you did well on some parts but badly on other parts? If
you could study only the bits you really enjoyed and were good at, you would
do better.
> 2. AFAIK, you need an MSc before you can even attempt a PhD.
Oh ok, I wasn't aware of that limitation (Engineering degrees are usually
all 4 years so of course this limitation wasn't mentioned to us).
> 3. I severely doubt that I could actually perform a PhD at the same time
> as doing a full-time job.
Why not? You could probably do a PhD instead of posting here :-)
> 4. I already have a BSc, and it hasn't opened any doors for me. I
> seriously doubt a PhD would be any significant help in this direction.
Oh I'm sure it would, today almost everyone has some sort of degree, having
a PhD will make you stand out from the crowd, much like having a degree a
few decades ago did. Besides, you will probably enjoy it, plus it will get
you into an enjoyable job later.
But yes, it could be a bit pricey to fund yourself.
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>> 1. I barely passed my BSc. Studying something even harder would seem
>> unwise.
>
> But let me guess, you did well on some parts but badly on other parts?
> If you could study only the bits you really enjoyed and were good at,
> you would do better.
I very much doubt you can actually do a PhD in "doing cool stuff with a
computer". It's a tad vague, eh?
>> 2. AFAIK, you need an MSc before you can even attempt a PhD.
>
> Oh ok, I wasn't aware of that limitation (Engineering degrees are
> usually all 4 years so of course this limitation wasn't mentioned to us).
My course was 4 years too, but it was only a BSc. I might be wrong about
the MSc requirement, but that's what I heard.
>> 3. I severely doubt that I could actually perform a PhD at the same
>> time as doing a full-time job.
>
> Why not? You could probably do a PhD instead of posting here :-)
LOL! Yeah, right. :-P
Besides, don't you have to, like, spend years searching through the
library to find every piece of work that has ever been written about
your subject, read and memorise it all, and then present a giant summary
of it? Don't you have to trudge across the plains of Tibet to find an
ancient sage to consult on the works on the Ancient Masters to see if
they have anything relevant to add? I don't think I could do that from
my desk at work.
>> 4. I already have a BSc, and it hasn't opened any doors for me. I
>> seriously doubt a PhD would be any significant help in this direction.
>
> Oh I'm sure it would, today almost everyone has some sort of degree,
> having a PhD will make you stand out from the crowd, much like having a
> degree a few decades ago did.
Meh. I doubt it. It seems everybody just asks "how many years' coding
experience do you have?" and "what are your customer service skills like?"
> Besides, you will probably enjoy it, plus
> it will get you into an enjoyable job later.
The former, perhaps, the latter, unlikely. (So those jobs still exist?)
> But yes, it could be a bit pricey to fund yourself.
Er, yes.
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And lo On Tue, 17 Feb 2009 11:45:40 -0000, Invisible <voi### [at] dev null> did
spake thusly:
> There now follows a large brain dump concerning knot theory...
Yay!
> At one time, it was briefly theorised that maybe the ~105 elements of
> the periodic table were each a little tangle of energy, and different
> kinds of tangling gave rise to different chemical properties.
>
> (With String Theory, the idea seems to be coming back somewhat. But I
> digress...)
Yeah interesting how some ideas can come back from the grave.
> So what actually *is* knot theory? Well, it's the study of mathematical
> "knots". As you might expect, these abstract entities have properties
> similar to but not quite the same as a real knot in a piece of string.
Also perhaps worth pointing out it's only one area of study in topology.
<snip>
> One rather entertaining way goes something like this. (I've probably
> screwed up the algorithm; this is from memory.)
>
> - Pick a starting point on the string, and draw an arrow representing a
> direction. Doesn't matter what you pick, but stick to it.
>
> - Trace your way around the knot. Each time you reach a crossing, number
> it, starting from 1. If the strand you're on goes over the top, use a
> positive number. If it goes under, assign a negative number.
Okay let's try the trefoil knot.
> - Write down a list of all the pairs of numbers at each crossing.
-1, 4
2, -5
-3, 6
> - Throw away the lowest number in each pair (ignoring sign).
Leaves 4,-5,6. Hmmm? Okay let's try that again following Dowker notation.
1,4
2,5
3,6
As this is an alternating knot, no changes in signs required.
Write out the odd numbers with corresponding entry beneath
1, 3, 5
4, 6, 2
Throw away the top numbers to leave 4,6,2.
> An alternative way to describe knots is by "braid theory".
>
> A "braid" is a series of vertical strands. Initially, they are all
> parallel. If you say "+3", that means that strand 3 and strand 4 swap
> places, with strand 3 going over the top of strand 4. Alternatively,
> "-3" means the same swap, but strand 4 going over the top.
>
> In this way, you can say "-3, +5, +2". This describes a sequence of
> strand swaps, starting from the top and working downwards. Something
> like this:
>
> 1 2 3 4 5 6
> | | | | | |
> | | \ / | |
> | | / | |
> | | / \ | |
> | | | | | |
> | | | | \ /
> | | | | \
> | | | | / \
> | | | | | |
> | \ / | | |
> | \ | | |
> | / \ | | |
> | | | | | |
> 1 2 3 4 5 6
>
> So that's a braid. Now if you imagine taking this and bending it over so
> that the ends at the top connect with the ends at the bottom, this would
> make a closed loop. In fact, in this case, the result would be *several*
> closed loops. The 1 strand would be an unknot, not connected to anything
> else. Strands 5 and 6 would become a single strand, which can then be
> untwizzled to make an unknot. And strands 2, 3 and 4 would be connected;
> off the top of my head, I'm not sure if this would be a nontrivial knot.
Trivial, It's a rubber-band twisted twice.
> This has been another broadcast brought to you by an under-employed
> computer science graduate, for the benefit of similarly over-interested
> souls. TTFN!
Interesting, polish it up and stick it on your blog.
--
Phil Cook
--
I once tried to be apathetic, but I just couldn't be bothered
http://flipc.blogspot.com
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Phil Cook v2 wrote:
> Yay!
See, that's what I'm talkin bout! :-D
> Also perhaps worth pointing out it's only one area of study in topology.
Yeah, but topology is friggin *weird*. Knot theory makes actual sense.
> Okay let's try the trefoil knot.
>
>> - Write down a list of all the pairs of numbers at each crossing.
>
> -1, 4
> 2, -5
> -3, 6
>
>> - Throw away the lowest number in each pair (ignoring sign).
>
> Leaves 4,-5,6. Hmmm? Okay let's try that again following Dowker notation.
>
> 1,4
> 2,5
> 3,6
>
> As this is an alternating knot, no changes in signs required.
>
> Write out the odd numbers with corresponding entry beneath
>
> 1, 3, 5
> 4, 6, 2
>
> Throw away the top numbers to leave 4,6,2.
See my other reply. I've got the algorithm wrong.
>> An alternative way to describe knots is by "braid theory".
>>
>> A "braid" is a series of vertical strands. Initially, they are all
>> parallel. If you say "+3", that means that strand 3 and strand 4 swap
>> places, with strand 3 going over the top of strand 4. Alternatively,
>> "-3" means the same swap, but strand 4 going over the top.
>>
>> In this way, you can say "-3, +5, +2". This describes a sequence of
>> strand swaps, starting from the top and working downwards. Something
>> like this:
>>
>> 1 2 3 4 5 6
>> | | | | | |
>> | | \ / | |
>> | | / | |
>> | | / \ | |
>> | | | | | |
>> | | | | \ /
>> | | | | \
>> | | | | / \
>> | | | | | |
>> | \ / | | |
>> | \ | | |
>> | / \ | | |
>> | | | | | |
>> 1 2 3 4 5 6
>>
>> So that's a braid. Now if you imagine taking this and bending it over
>> so that the ends at the top connect with the ends at the bottom, this
>> would make a closed loop. In fact, in this case, the result would be
>> *several* closed loops. The 1 strand would be an unknot, not connected
>> to anything else. Strands 5 and 6 would become a single strand, which
>> can then be untwizzled to make an unknot. And strands 2, 3 and 4 would
>> be connected; off the top of my head, I'm not sure if this would be a
>> nontrivial knot.
>
> Trivial, It's a rubber-band twisted twice.
Probably. Actually, wait - there are only 2 crossings. No nontrivial
knot has that few. Yes, it's definitely trivial. *sigh* Rusty...
>> This has been another broadcast brought to you by an under-employed
>> computer science graduate, for the benefit of similarly
>> over-interested souls. TTFN!
>
> Interesting, polish it up and stick it on your blog.
Now, see, when I spend ages writing something like this, I kinda want
people to go "hey, that's interesting. I had no idea this crap even
existed!" But typically they go "OK, that's nice dear".
I just wish I could find a place where the stuff I know would actually
impress people... *sigh*
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> I very much doubt you can actually do a PhD in "doing cool stuff with a
> computer".
Of course you can, just substitute "cool stuff" for a subject that you
actually find cool.
> Besides, don't you have to, like, spend years searching through the
> library to find every piece of work that has ever been written about your
> subject, read and memorise it all, and then present a giant summary of it?
> Don't you have to trudge across the plains of Tibet to find an ancient
> sage to consult on the works on the Ancient Masters to see if they have
> anything relevant to add? I don't think I could do that from my desk at
> work.
Depends on the subject of course, but nowadays I think most journals and
other academic resources are available online. For a computing related PhD
I would imagine most of your time will be spent at the computer.
> Meh. I doubt it. It seems everybody just asks "how many years' coding
> experience do you have?" and "what are your customer service skills like?"
If you have a PhD you are not going to be applying for those sorts of jobs,
and more importantly companies are not going to expect you to be a code
monkey 24/7 when you are much more capable than that.
Here's an interesting CV:
http://www.geisswerks.com/ryan/resume_ryan_geiss.doc
See, just write something cool *and actually finish it* and then everyone
wants to employ you!
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>> I very much doubt you can actually do a PhD in "doing cool stuff with
>> a computer".
>
> Of course you can, just substitute "cool stuff" for a subject that you
> actually find cool.
Such as...?
There's lots of stuff that interests me, but none of it is exactly "new"
or "revolutionary".
> Depends on the subject of course, but nowadays I think most journals and
> other academic resources are available online. For a computing related
> PhD I would imagine most of your time will be spent at the computer.
Well, I guess it depends on what precisely you wanted to tackle. Either
way, I suck at research, so...
>> Meh. I doubt it. It seems everybody just asks "how many years' coding
>> experience do you have?" and "what are your customer service skills
>> like?"
>
> If you have a PhD you are not going to be applying for those sorts of
> jobs, and more importantly companies are not going to expect you to be a
> code monkey 24/7 when you are much more capable than that.
Yes, but does anybody actually employ PhDs? Most of the ones I know of
still hang around universities...
> Here's an interesting CV:
>
> http://www.geisswerks.com/ryan/resume_ryan_geiss.doc
>
> See, just write something cool *and actually finish it* and then
> everyone wants to employ you!
"Seeking: Collaboration with a group of smart, creative people, in order
to produce work of practical or aesthetic value to mankind."
...OK, that's pretty special, right there. o_O
But then, we *are* talking about the legendary Ryan Geiss... (I bet he's
Polish or something! All the best programmers are, for some reason.)
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>> Of course you can, just substitute "cool stuff" for a subject that you
>> actually find cool.
>
> Such as...?
>
> There's lots of stuff that interests me, but none of it is exactly "new"
> or "revolutionary".
People are doing PhDs in lots of things that you seem to be interested in,
quick Google results:
http://www.liv.ac.uk/~su14/knotgroup.html
http://www.ph.tn.tudelft.nl/PRInfo/reports/msg00512.html
http://research.microsoft.com/en-us/groups/vision/default.aspx
Just try googling "PhD "+thing you are interested in. You will be surprised
what is on offer. I was surprised to hear from my 4th year project
supervisor that if I wanted I could carry on my project "how brake pedal
feedback in vehicles affects driver response" as a PhD, I would have thought
such a specialist topic to be of no interest to anyone, but now I see how
companies would be very interested.
> Well, I guess it depends on what precisely you wanted to tackle. Either
> way, I suck at research, so...
You seem to have demonstrated otherwise here, frequently you seem to have
taken ideas and material and then expanded upon it yourself. It doesn't
matter if you were unaware that someone else had already done the same, if
you were doing a real PhD you would search a bit more thoroughly before
starting work.
> Yes, but does anybody actually employ PhDs? Most of the ones I know of
> still hang around universities...
Over half the people working at my employer in Oxford have PhDs, it's mainly
a research lab (my department is the exception, we deal with developing
technology for specific customers). Surely a lot of people at your place
have PhDs too? I think a lot of people who hand around Universities do so
because they want to (they just enjoy academia) rather than because they
can't find a job outside.
People with the PhDs are the ones inventing new things at the concept stage,
then the Engineers like me get to work out how to actually make it into a
product :-)
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scott wrote:
>>> Of course you can, just substitute "cool stuff" for a subject that
>>> you actually find cool.
>>
>> Such as...?
>>
>> There's lots of stuff that interests me, but none of it is exactly
>> "new" or "revolutionary".
>
> People are doing PhDs in lots of things that you seem to be interested
> in, quick Google results:
>
> Just try googling "PhD "+thing you are interested in. You will be
> surprised what is on offer. I was surprised to hear from my 4th year
> project supervisor that if I wanted I could carry on my project "how
> brake pedal feedback in vehicles affects driver response" as a PhD, I
> would have thought such a specialist topic to be of no interest to
> anyone, but now I see how companies would be very interested.
I'm still impressed about the guy who got a grant to find out whether or
not a duck's quack really does echo. WTF?
>> Well, I guess it depends on what precisely you wanted to tackle.
>> Either way, I suck at research, so...
>
> You seem to have demonstrated otherwise here, frequently you seem to
> have taken ideas and material and then expanded upon it yourself. It
> doesn't matter if you were unaware that someone else had already done
> the same, if you were doing a real PhD you would search a bit more
> thoroughly before starting work.
Surfing Wikipedia for a few hours is one thing. Somehow finding and
actually reading academic papers is much harder. (I failed epically at
this last time around...)
>> Yes, but does anybody actually employ PhDs? Most of the ones I know of
>> still hang around universities...
>
> Over half the people working at my employer in Oxford have PhDs, it's
> mainly a research lab (my department is the exception, we deal with
> developing technology for specific customers). Surely a lot of people
> at your place have PhDs too? I think a lot of people who hand around
> Universities do so because they want to (they just enjoy academia)
> rather than because they can't find a job outside.
I don't think I've ever met anybody who has a PhD. (Of course, it's not
like they have labels on them, so I can't be sure...) Most of the people
who work here have degrees.
Most worryingly, I don't think anybody I met at uni had a PhD either... o_O
> People with the PhDs are the ones inventing new things at the concept
> stage, then the Engineers like me get to work out how to actually make
> it into a product :-)
Heh, yeah.
I asked on IRC, and got this:
http://www.nigels.com/jokes/phd1.pdf
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"scott" <sco### [at] scottcom> wrote in message
news:499ade73$1@news.povray.org...
> People with the PhDs are the ones inventing new things at the concept
> stage, then the Engineers like me get to work out how to actually make it
> into a product :-)
Wow, what a good job that is. I'd love a job like that.
~Steve~
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>> People with the PhDs are the ones inventing new things at the concept
>> stage, then the Engineers like me get to work out how to actually make it
>> into a product :-)
>
> Wow, what a good job that is. I'd love a job like that.
What the PhD or the Engineer?
It made me laugh when one of the other departments here announced that one
of their new projects for the next 6 months was to find ideas for new
research projects :-)
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> I asked on IRC, and got this:
>
> http://www.nigels.com/jokes/phd1.pdf
Not to mention this...
http://www.dcs.ed.ac.uk/home/pgh/thesis.html
Nice. :-S
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> I'm still impressed about the guy who got a grant to find out whether or
> not a duck's quack really does echo. WTF?
Exactly, if he can get that then you should be sorted!
> I don't think I've ever met anybody who has a PhD. (Of course, it's not
> like they have labels on them, so I can't be sure...)
But usually they are listed as "Dr" in organisation charts, on business
cards, publications, email names etc.
Most of the people I know who have any position of responsibility in the
companies I deal with have a PhD, it's not a coincidence, it definitely
helps you in your career.
> Most worryingly, I don't think anybody I met at uni had a PhD either...
> o_O
Hmm, most of my lecturers and supervisors were Dr something, or occasionally
students working for their PhDs.
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"scott" <sco### [at] scottcom> wrote in message
news:499ae4d5$1@news.povray.org...
>>> People with the PhDs are the ones inventing new things at the concept
>>> stage, then the Engineers like me get to work out how to actually make
>>> it into a product :-)
>>
>> Wow, what a good job that is. I'd love a job like that.
>
> What the PhD or the Engineer?
Oh, being that type of Engineer. See if this works, see if that works, try
this material, is it too heavy, too light, is it safe, etc.
I'd love that.
>
> It made me laugh when one of the other departments here announced that one
> of their new projects for the next 6 months was to find ideas for new
> research projects :-)
Heh, quite hard to do I would think, especially as, (as Andrew would say),
"Everything in the whole entire universe has already been invented." :)
Personally, I think there's a whole lot of good things to come yet. I
wonder what the very last invention ever would be?
~Steve~
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> Oh, being that type of Engineer. See if this works, see if that works,
> try this material, is it too heavy, too light, is it safe, etc.
At the moment it's more like "see if it can be mass-produced cheaper than
what we make at the moment" - everything else doesn't seem to matter!
> Heh, quite hard to do I would think, especially as, (as Andrew would say),
> "Everything in the whole entire universe has already been invented." :)
>
> Personally, I think there's a whole lot of good things to come yet. I
> wonder what the very last invention ever would be?
The guys here tend to work on improvements to existing stuff, mostly optics
and LCD based things. They seem to churn out a lot of patents on those
subjects but most of which I think "nah, that's never going to be
practical". For instance they came up with the dual-view LCD display which
is just about to make it into cars -
http://www.engadget.com/2008/12/10/mercedes-benz-intros-splitview-command-system/
but it's just too expensive to manufacture and nobody really wants to pay
the premium so I don't see it becoming popular anytime soon.
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On 17-2-2009 17:11, Invisible wrote:
> scott wrote:
>
> I'm still impressed about the guy who got a grant to find out whether or
> not a duck's quack really does echo. WTF?
I am not sure that is true. Anyway I saw it both on Brainiac and on
Mythbusters tried and falsified.
>>> Well, I guess it depends on what precisely you wanted to tackle.
>>> Either way, I suck at research, so...
>>
>> You seem to have demonstrated otherwise here, frequently you seem to
>> have taken ideas and material and then expanded upon it yourself. It
>> doesn't matter if you were unaware that someone else had already done
>> the same, if you were doing a real PhD you would search a bit more
>> thoroughly before starting work.
>
> Surfing Wikipedia for a few hours is one thing. Somehow finding and
> actually reading academic papers is much harder. (I failed epically at
> this last time around...)
I still think you should try. But there is the problem of that BSc.
BTW I am also not very good at reading papers. I have this problem that
I get distracted by possibly unrelated ideas popping into my head so
often that I can hardly finish a sentence. The only place I can read
seems to be in bath. That cuts the reading time to about an hour per
week. I should read at least 4 or 5 hours so...
>>> Yes, but does anybody actually employ PhDs? Most of the ones I know
>>> of still hang around universities...
There should be a couple in your company. At least in the US, but given
what you do, also at least one in the UK. (if there isn't one, that may
explain some things).
>> Over half the people working at my employer in Oxford have PhDs, it's
>> mainly a research lab (my department is the exception, we deal with
>> developing technology for specific customers). Surely a lot of people
>> at your place have PhDs too? I think a lot of people who hand around
>> Universities do so because they want to (they just enjoy academia)
>> rather than because they can't find a job outside.
>
> I don't think I've ever met anybody who has a PhD.
At least you met a couple on line.
> (Of course, it's not
> like they have labels on them, so I can't be sure...) Most of the people
> who work here have degrees.
What degrees would that be?
> Most worryingly, I don't think anybody I met at uni had a PhD either... o_O
Could be. In other disciplines than computer science it is quite rare
not to have mainly PhD's in the staff.
>> People with the PhDs are the ones inventing new things at the concept
>> stage, then the Engineers like me get to work out how to actually make
>> it into a product :-)
>
> Heh, yeah.
Here the interpretation of a PhD is that you are able to define and do
your own research.
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On 17-2-2009 17:41, St. wrote:
>
> Personally, I think there's a whole lot of good things to come yet. I
> wonder what the very last invention ever would be?
>
> ~Steve~
Either something that explodes unexpectedly or a black hole.
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"andrel" <a_l### [at] hotmailcom> wrote in message
news:499### [at] hotmailcom...
> On 17-2-2009 17:41, St. wrote:
>>
>> Personally, I think there's a whole lot of good things to come yet. I
>> wonder what the very last invention ever would be?
>>
>> ~Steve~
>
> Either something that explodes unexpectedly
Yes, like those two nuke subs that collided, (was it last week?)
Imagine if they'd have exploded. What would we be doing right now?
> or a black hole.
But that's not an invention, or do you mean, (in the future), an invented
black hole?
~Steve~
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>> I'm still impressed about the guy who got a grant to find out whether
>> or not a duck's quack really does echo. WTF?
>
> I am not sure that is true.
Well, I saw the team interviewed on the local news station, together
with the duck they used for their experiments. The researcher (who
looked like a lad from down the pub to me) stated that a duck's quack
does, in fact, echo, and it is merely that ducks are not usually found
in places where you would expect to find echoes.
> Anyway I saw it both on Brainiac and on
> Mythbusters tried and falsified.
Unsurprisingly.
>> Surfing Wikipedia for a few hours is one thing. Somehow finding and
>> actually reading academic papers is much harder. (I failed epically at
>> this last time around...)
>
> I still think you should try. But there is the problem of that BSc.
> BTW I am also not very good at reading papers. I have this problem that
> I get distracted by possibly unrelated ideas popping into my head so
> often that I can hardly finish a sentence. The only place I can read
> seems to be in bath. That cuts the reading time to about an hour per
> week. I should read at least 4 or 5 hours so...
Some of the papers on GHC are really well-written. (Mind you, I showed
you SPJ's advice on writing a paper, right?)
>>>> Yes, but does anybody actually employ PhDs? Most of the ones I know
>>>> of still hang around universities...
>
> There should be a couple in your company. At least in the US, but given
> what you do, also at least one in the UK. (if there isn't one, that may
> explain some things).
Our boss sometimes introduces himself as "Doctor". OTOH, he's an idiot.
And a self-important idiot at that.
>> (Of course, it's not like they have labels on them, so I can't be
>> sure...) Most of the people who work here have degrees.
>
> What degrees would that be?
Chemistry, mostly.
>> Most worryingly, I don't think anybody I met at uni had a PhD
>> either... o_O
>
> Could be. In other disciplines than computer science it is quite rare
> not to have mainly PhD's in the staff.
Most of our staff seemed to be random Polish/Scandinavian/Ethiopian
people with a vague grasp of English.
Not that I wish to imply that not speaking English is a bad thing, but
when you're paid to speak to people in English, it would seem a
necessary job requirement...
--
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*
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Invisible wrote:
> I very much doubt you can actually do a PhD in "doing cool stuff with a
> computer". It's a tad vague, eh?
The way it works (here at least) is that there is someone who is sponsoring
and tutoring you called your "adviser". He has a particular area of interest
(like compiler construction, network protocols, or whatever), and he helps
you pick a topic that would be interesting, publishable, etc.
So what you need to do if you want a PhD in something you find interesting
is go to universities and find out what potential advisers are interested
in. You won't be able to do a PhD on Haskell compiler optimizations if
nobody at the university is interested in compilers.
> My course was 4 years too, but it was only a BSc. I might be wrong about
> the MSc requirement, but that's what I heard.
I said that's true of the places I looked in the US, and someone
contradicted me and said the UK works differently.
> Besides, don't you have to, like, spend years searching through the
> library to find every piece of work that has ever been written about
> your subject,
No. That's why you have an adviser. He tells you where to look for related
information. There's a lot of reading and understanding, and you need to
summarize it enough to show why what you're doing is different, but that's
about it.
> ancient sage to consult on the works on the Ancient Masters to see if
> they have anything relevant to add?
That's why they invented university libraries. :-)
> I don't think I could do that from my desk at work.
I was often met with astounded surprised when I mentioned that I was paying
my own tuition. You don't need a job to get a PhD if you get accepted.
> Meh. I doubt it. It seems everybody just asks "how many years' coding
> experience do you have?" and "what are your customer service skills like?"
You'd be applying for different jobs.
--
Darren New, San Diego CA, USA (PST)
"Ouch ouch ouch!"
"What's wrong? Noodles too hot?"
"No, I have Chopstick Tunnel Syndrome."
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Invisible wrote:
> Meh. I doubt it. It seems everybody just asks "how many years' coding
> experience do you have?" and "what are your customer service skills like?"
Oh, btw, all that research and climbing mountains to see the sages and
stuff? They're the people that hire you when you graduate. Part of the PhD
is being in touch with hundreds of people interested in working on the same
thing you are.
--
Darren New, San Diego CA, USA (PST)
"Ouch ouch ouch!"
"What's wrong? Noodles too hot?"
"No, I have Chopstick Tunnel Syndrome."
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Invisible wrote:
> Surfing Wikipedia for a few hours is one thing. Somehow finding and
> actually reading academic papers is much harder. (I failed epically at
> this last time around...)
If you already know how to do this, you wouldn't need to learn it. Figuring
out how to find and read academic papers is part of what you learn.
> Most worryingly, I don't think anybody I met at uni had a PhD either... o_O
None of the professors had PhD's? Heck, the science teachers in my high
school had PhDs.
--
Darren New, San Diego CA, USA (PST)
"Ouch ouch ouch!"
"What's wrong? Noodles too hot?"
"No, I have Chopstick Tunnel Syndrome."
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St. wrote:
> Personally, I think there's a whole lot of good things to come yet. I
> wonder what the very last invention ever would be?
Grey goo.
--
Darren New, San Diego CA, USA (PST)
"Ouch ouch ouch!"
"What's wrong? Noodles too hot?"
"No, I have Chopstick Tunnel Syndrome."
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St. wrote:
> "andrel" <a_l### [at] hotmailcom> wrote in message
> news:499### [at] hotmailcom...
>> On 17-2-2009 17:41, St. wrote:
>>> Personally, I think there's a whole lot of good things to come yet. I
>>> wonder what the very last invention ever would be?
>>>
>>> ~Steve~
>> Either something that explodes unexpectedly
>
> Yes, like those two nuke subs that collided, (was it last week?)
>
> Imagine if they'd have exploded. What would we be doing right now?
Assuming you mean if the weapons went off - not much chance of that. I
reckon those subs could be completely destroyed by a variety of
accidents/hostilities and the nukes still wouldn't go off. They need to
be set off deliberately.
> > or a black hole.
>
> But that's not an invention, or do you mean, (in the future), an invented
> black hole?
Maybe like the black holes those sciern-tists are going to create in the
LHC and irresponsibly wipe us off the map, or so I read in the papers ;-)
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On 17-2-2009 19:39, Darren New wrote:
> Invisible wrote:
>> I very much doubt you can actually do a PhD in "doing cool stuff with
>> a computer". It's a tad vague, eh?
>
> The way it works (here at least) is that there is someone who is
> sponsoring and tutoring you called your "adviser". He has a particular
> area of interest (like compiler construction, network protocols, or
> whatever), and he helps you pick a topic that would be interesting,
> publishable, etc.
Things work sometimes a bit different here. I did mine while working on
some projects. Though graduation was not part of the job description,
after some years my choice was write a thesis or look for another job. I
didn't want to do either, but chose the lesser evil.
In our lab it is not uncommon if a lab technician gets a PhD. Then again
we do have some very good ones.
> So what you need to do if you want a PhD in something you find
> interesting is go to universities and find out what potential advisers
> are interested in. You won't be able to do a PhD on Haskell compiler
> optimizations if nobody at the university is interested in compilers.
>
>> My course was 4 years too, but it was only a BSc. I might be wrong
>> about the MSc requirement, but that's what I heard.
>
> I said that's true of the places I looked in the US, and someone
> contradicted me and said the UK works differently.
As far as I know it you need a MSc or equivalent in the Netherlands.
Though things have shifted a bit, perhaps 4 years of BSc may be
equivalent to something here. Andy graduated before the European
normalization of grades, so I would need to ask foreign affairs in his
case.
>> Besides, don't you have to, like, spend years searching through the
>> library to find every piece of work that has ever been written about
>> your subject,
>
> No. That's why you have an adviser. He tells you where to look for
> related information. There's a lot of reading and understanding, and you
> need to summarize it enough to show why what you're doing is different,
> but that's about it.
>
>> ancient sage to consult on the works on the Ancient Masters to see if
>> they have anything relevant to add?
>
> That's why they invented university libraries. :-)
Actually the citable history for many students is whatever is on-line.
Nobody uses the library anymore. Unfortunately people are scanning in
old years of the main journals.
>> I don't think I could do that from my desk at work.
>
> I was often met with astounded surprised when I mentioned that I was
> paying my own tuition. You don't need a job to get a PhD if you get
> accepted.
>
>> Meh. I doubt it. It seems everybody just asks "how many years' coding
>> experience do you have?" and "what are your customer service skills
>> like?"
>
> You'd be applying for different jobs.
I agree, he is looking for the wrong jobs ;) He looks for jobs where he
can do things that he thinks are interesting. He should look for a job
in something that he is good in, make himself irreplaceable and grow
from there. That may look like the long path, but staying with his
current job won't bring him anywhere either.
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andrel wrote:
> Actually the citable history for many students is whatever is on-line.
> Nobody uses the library anymore. Unfortunately people are scanning in
> old years of the main journals.
Wow, that sucks. I can't imagine paying for myself subscriptions to every
lame-ass journal I ever had to look something up in. It's almost criminal
how places like IEEE and ACM will take your work, publish it, then charge
you to have a copy of it.
--
Darren New, San Diego CA, USA (PST)
"Ouch ouch ouch!"
"What's wrong? Noodles too hot?"
"No, I have Chopstick Tunnel Syndrome."
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Darren New wrote:
> andrel wrote:
>> Actually the citable history for many students is whatever is on-line.
>> Nobody uses the library anymore. Unfortunately people are scanning in
>> old years of the main journals.
>
> Wow, that sucks. I can't imagine paying for myself subscriptions to
> every lame-ass journal I ever had to look something up in. It's almost
> criminal how places like IEEE and ACM will take your work, publish it,
> then charge you to have a copy of it.
Don't they give you a digital copy free though?
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Am Tue, 17 Feb 2009 14:24:54 -0800 schrieb Darren New:
> andrel wrote:
>> Actually the citable history for many students is whatever is on-line.
>> Nobody uses the library anymore. Unfortunately people are scanning in
>> old years of the main journals.
>
> Wow, that sucks. I can't imagine paying for myself subscriptions to
> every lame-ass journal I ever had to look something up in. It's almost
> criminal how places like IEEE and ACM will take your work, publish it,
> then charge you to have a copy of it.
Subscriptions to the journals are usually paid for by the university here
(in Germany and I would guess it is the same in he Netherlands?) so if
you have access to the university network you usually have access to most
journals.
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On 17-2-2009 23:24, Darren New wrote:
> andrel wrote:
>> Actually the citable history for many students is whatever is on-line.
>> Nobody uses the library anymore. Unfortunately people are scanning in
>> old years of the main journals.
>
> Wow, that sucks. I can't imagine paying for myself subscriptions to
> every lame-ass journal I ever had to look something up in. It's almost
> criminal how places like IEEE and ACM will take your work, publish it,
> then charge you to have a copy of it.
Most libraries have on-line subscription, so everything is the same
except that you don't have to go to the library anymore, but download
the PDF yourself. In case it wasn't clear, I meant unfortunate for the
student as they can access (and may have to read) much more than a year
extra every year.
10 years ago everybody used the library, so you could see citations of
20 years back or more. Then suddenly journals came on-line and the
citation horizon dropped to about 5 years (except for second hand
citations of papers they did not actually read of course). Now the
citation period is almost back to what it was and even on the way of
exceeding that, because of scanned journals.
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On 17-2-2009 23:34, Florian Pesth wrote:
> Am Tue, 17 Feb 2009 14:24:54 -0800 schrieb Darren New:
>
>> andrel wrote:
>>> Actually the citable history for many students is whatever is on-line.
>>> Nobody uses the library anymore. Unfortunately people are scanning in
>>> old years of the main journals.
>> Wow, that sucks. I can't imagine paying for myself subscriptions to
>> every lame-ass journal I ever had to look something up in. It's almost
>> criminal how places like IEEE and ACM will take your work, publish it,
>> then charge you to have a copy of it.
>
> Subscriptions to the journals are usually paid for by the university here
> (in Germany and I would guess it is the same in he Netherlands?) so if
> you have access to the university network you usually have access to most
> journals.
True.
BTW I do have this interesting problem of being in a academic hospital
with access to most medical journals, but not the Biomedical Engineering
ones. So when I am peer reviewing a paper and want to check a reference,
I have to resort to my paper versions at home of the IEEE EMBS, that I
can't throw away for that reason and for another journal I sometimes ask
the editor if he can get me a copy. I find that a bit annoying, perhaps
I should take a partial appointment at a technical university.
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> None of the professors had PhD's? Heck, the science teachers in my high
> school had PhDs.
At my University it seemed to be a requirement that to become a professor
you need a PhD (this is for the UK definition of Professor, which means you
are head of department or some other very senior role, my understanding is
that this is not the same in the US).
At my first school only the headmaster had a PhD, but at the school I did my
A-levels at (16-18 years old) a lot of the science and maths teachers had
PhDs.
Off topic, my pure maths teacher was the coolest ever, the stereotypical
maths geek aged about 40 complete with holey wooly jumper and beard. He was
fond of writing on peoples end of year reports (where there was space for
about 10-15 lines) 3 word summaries.
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>> Imagine if they'd have exploded. What would we be doing right now?
>
> Assuming you mean if the weapons went off - not much chance of that. I
> reckon those subs could be completely destroyed by a variety of
> accidents/hostilities and the nukes still wouldn't go off. They need to be
> set off deliberately.
Yes, it is almost impossible to set off the nuclear weapon "by mistake" due
to some shock or explosion nearby, *but* the radioactive components of the
weapon can sure be released during a normal impact/explosion and released
into the water or atmosphere. It may not be as severe as a nuclear
explosion, but there will be a lot of radioactive material released, and the
sea currents / wind will probably carry it and dump it as rain over
Europe...
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On 18-2-2009 9:01, scott wrote:
>> None of the professors had PhD's? Heck, the science teachers in my
>> high school had PhDs.
>
> At my University it seemed to be a requirement that to become a
> professor you need a PhD (this is for the UK definition of Professor,
> which means you are head of department or some other very senior role,
> my understanding is that this is not the same in the US).
In the Netherlands it is not a requirement, but uncommon. The most
common cause is that they wanted a person from a company as professor.
As a non-PhD professor you can not act as the promotor for a PhD. You
can do the daily supervision, but for the actual defence you need
another professor that does have it's PhD.
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scott wrote:
>>> Imagine if they'd have exploded. What would we be doing right now?
>>
>> Assuming you mean if the weapons went off - not much chance of that. I
>> reckon those subs could be completely destroyed by a variety of
>> accidents/hostilities and the nukes still wouldn't go off. They need
>> to be set off deliberately.
>
> Yes, it is almost impossible to set off the nuclear weapon "by mistake"
> due to some shock or explosion nearby, *but* the radioactive components
> of the weapon can sure be released during a normal impact/explosion and
> released into the water or atmosphere. It may not be as severe as a
> nuclear explosion, but there will be a lot of radioactive material
> released, and the sea currents / wind will probably carry it and dump it
> as rain over Europe...
I don't think that would be particularly serious either. The sub's
reactor would probably be more dangerous than the warheads in that regard.
Obviously a spilled warhead wouldn't be harmless, but I'm not convinced
that large masses of dense metals such as Pu and U would make it very
far, least of all rainfall! And I'd like to believe that the sub's
designers might have though of this too... :)
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> andrel wrote:
> Wow, that sucks. I can't imagine paying for myself subscriptions to
> every lame-ass journal I ever had to look something up in. It's almost
> criminal how places like IEEE and ACM will take your work, publish it,
> then charge you to have a copy of it.
Actually, among the abusers, professional societies like IEEE and APS
are quite mild.
The guys who really charge an arm and a leg are the private for-profit
publishers like Elsevier and Springer.
Not an ACM member, but someone told me that every member gets access to
all their journals. With IEEE, you have to become a member, and then pay
for each journal you want to access. For individuals, it's very unlikely
to be worth it.
And yes, I agree the amount they charge for a given article (if you
just want that one) is also ridiculous. It may be OK if you _really_
know that's the article you want, but if you're just doing ordinary
research, you'll have to go through dozens of papers.
In any case, I've often heard that if you really want a paper, just
email the author and they'll send it to you. Haven't put it to the test.
I've also heard that over the last few years, a number of professional
societies (one or both of the US physics ones, and perhaps IEEE as well)
actually do allow you to put preprints online or on places like arxiv.
Preprints here meaning the version of the paper that has finally been
approved for publication (so pretty much the same paper). The condition
is simply that wherever you post it, you cite the actual IEEE paper.
So those guys really aren't all that bad. I know Applied Physics
Letters allows you to make your paper open access if you (the author)
pay a fee - close to $1000 (usually comes from the grant that paid for
the research). That may sound like a disincentive, but do realize that
many of the prominent open access journals actually charge similar
rates. I hear IEEE also has a similar fee if you want your paper to be
open access.
--
Engineers: often wrong, seldom in doubt.
/\ /\ /\ /
/ \/ \ u e e n / \/ a w a z
>>>>>>mue### [at] nawazorg<<<<<<
anl
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Mueen Nawaz wrote:
> The guys who really charge an arm and a leg are the private for-profit
> publishers like Elsevier and Springer.
They're pretty bad too. And the conference proceedings are awfully
expensive if you can even get them, too.
> Not an ACM member, but someone told me that every member gets access to
> all their journals.
Maybe online these days. There were definitely subscription fees for the
paper versions back when I was still doing that sort of thing.
> And yes, I agree the amount they charge for a given article (if you
> just want that one) is also ridiculous. It may be OK if you _really_
> know that's the article you want, but if you're just doing ordinary
> research, you'll have to go through dozens of papers.
Yeah. I think the idea is you read it in the library or something, and then
you want a copy, so you buy one instead of just using the photocopier. I
don't know about nowadays, but it used to be that you'd order articles from
places that warehoused several copies of the magazines and someone would
manually sit down and cut out the article to send to you. Again, I suspect
now that everything's online this is different. :-)
> In any case, I've often heard that if you really want a paper, just
> email the author and they'll send it to you. Haven't put it to the test.
Probably, yeah. :-)
> I've also heard that over the last few years, a number of professional
> societies (one or both of the US physics ones, and perhaps IEEE as well)
> actually do allow you to put preprints online or on places like arxiv.
Apparently not ACM. I've seen a number of online papers taken down because
the copyright was signed over to ACM.
--
Darren New, San Diego CA, USA (PST)
"Ouch ouch ouch!"
"What's wrong? Noodles too hot?"
"No, I have Chopstick Tunnel Syndrome."
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Darren New wrote:
>> Not an ACM member, but someone told me that every member gets
>> access to
>> all their journals.
>
> Maybe online these days. There were definitely subscription fees for the
> paper versions back when I was still doing that sort of thing.
Yes - I meant for online. Who subscribes to paper versions anymore -
other than institutions?
>> I've also heard that over the last few years, a number of professional
>> societies (one or both of the US physics ones, and perhaps IEEE as well)
>> actually do allow you to put preprints online or on places like arxiv.
>
> Apparently not ACM. I've seen a number of online papers taken down
> because the copyright was signed over to ACM.
But were those the actual ACM articles, or the preprints? You still
can't post the former without permission.
--
Light travels faster than sound. This is why some people appear bright
until you hear them speak.
/\ /\ /\ /
/ \/ \ u e e n / \/ a w a z
>>>>>>mue### [at] nawazorg<<<<<<
anl
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Mueen Nawaz wrote:
> Yes - I meant for online. Who subscribes to paper versions anymore -
> other than institutions?
I haven't really done the academic paper stuff since the times of paper. :-)
> But were those the actual ACM articles, or the preprints? You still
> can't post the former without permission.
They were papers published by researchers, left online for many months, then
taken down when they were accepted to ACM publications. The links to the
papers were replaced to links to "please pay the ACM for these papers."
--
Darren New, San Diego CA, USA (PST)
"Ouch ouch ouch!"
"What's wrong? Noodles too hot?"
"No, I have Chopstick Tunnel Syndrome."
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