Orchid XP v8 wrote:
> I've already done this several times. I still don't comprehend.

OK, you understand boolean "and" and boolean "or", right? This is called 
"propositional logic":

   If it rains, the street is wet.
   It is raining.
   Therefore the street is wet.
That's propositional logic.

Go the next step, and you get first order predicate logic:
   All ravens are black.
   My bird is a raven.
   Therefore my bird is black.

The "all X are Y" is universal quantification.

If you have "some X is Y", that's existential quantification. Usually it's 
part of an expression involving universal quantification, like
   "for all integers X, there exists a integer Y such that
      if X is prime then Y is prime and Y > X."
That's just saying there's no biggest prime. No matter what
number we pick, if it's prime, there's some other number that's
also prime and larger. (It's not a proof, just a statement of
a boolean value. Proving the boolean is true is a separate step.)

Note also that the result is *one* boolean value. It's either true for all 
X, or it isn't.

There are, of course, standard rules of deduction, like
   "for all X, pred(X)"
is the same as
   "not for some X, not pred(X)"
and so on.



You might be getting stuck by reading too low in the explanation stack. Try
http://en.wikipedia.org/wiki/First_order_predicate_logic



-- 
   Darren New, San Diego CA, USA (PST)
   My fortune cookie said, "You will soon be
   unable to read this, even at arm's length."

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