Re: Why Python When There Is Perl?

On Sat, 23 Mar 2024 17:11:00 -0500, Physfitfreak wrote:

 
The second and fourth cases should both be false, not true.
 
In the second case (~A => B), non-prime isn't necessarily odd, and
therefore ~A does _not_ imply B, so result is false, not true.
 

You are reading it wrong.

The problem, I suppose, is the use of the word "implies."  This
should not be taken literally.

If a number is not prime, then could it be odd?  This is the
correct way to to interpret "~A => B."  The answer is "yes"
and the condition is true.

Similarly, the fourth case, "~A => ~B," should be interpreted
as "if a number is not prime, could it be even?"  The answer
is "yes" and hence the statement is true.

The second case, again, says, if a number is prime could it
be even?  The answer is "no" and hence false.

Again, the use of words obscures the mathematical reality.
It is proven that "A => B" is equivalent to "~A OR B" and
the negation (falsification) is "A AND ~B."

If it is raining (A), could the sky be cloudy (B)?  Yes.

If it is raining (A), could the sky be not cloudy (~B)?  No.

If it is not raining (~A), could the sky be cloudy (B)?  Yes.

If it is not raining (~A), could the sky be not cloudy (~B)?  Yes.

These are word games, however.  The mathematical definition
is that A => B is equivalent to "~A OR B."