Re: Why Python When There Is Perl?

On 3/23/2024 5:09 AM, Farley Flud wrote:

A is all prime numbers <= 100
 B is all odd numbers <= 100
 We have 4 possibilities:
 A => B: true
A number is prime implies it is odd.  Another, more proper,
way to state this is that if a number is in set A (prime)
then it is also in set B.
 ~A => B: true
If a number is not prime then it is odd.  The set of ~A
includes all the even numbers as well as all the odd numbers
in B.  This statement actually says that a number being not
prime as well as odd is a possibility because ~A includes B.
 A => ~B: false
Obviously, if a number is prime it cannot be not odd, that is,
if a number is in set A (prime) it cannot be in set ~B (even
numbers).
 ~A => ~B: true
Again, if a number is not in set A, the evens and all non-prime
odds, then it may be also not in set B, the non-prime odds.

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.
In the fourth case (~A => ~B), non-prime isn't necessarily even, and therefore ~A doesn't imply ~B, so result is false, not true.
And looking at the four results, one can see that we have three false result and one true result (first case).
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