In article , Robert Casey
writes:

WA3IYC wrote:

No, I mean "knowledge of". Skills are a form of knowledge, as are facts and
concepts. Perhaps it would be better to write "practical knowledge"

For example, consider base 10 natural number arithmetic

"2 + 2 = 4" is a fact.

"Addition is a mathematical operation in which two numbers are combined to
get
a third number which is never less than either of the first two numbers" is
a
concept.


Not quite.

Yes, quite. "Base 10 natural number arithmetic" does not include negative
numbers.

What if the numbers are 2 and -8? Negative numbers are
valid numbers.....

Not in the arithmetic of natural numbers...

Now if you want to talk about real numbers, or integers, or rational numbers...

Mathematicians have fun with this sort of thing. Called "proofs", which
I never did really understand in calculus class anyway.

Ah yes..

73 de Jim, N2EY