Dr.Peterson
Elite Member
- Joined
- Nov 12, 2017
- Messages
- 16,618
Yes, you could say of somebody that he is one of the two oldest siblings in his family, but do you find it appropriate to say that somebody is "an oldest sibling"? I think that you do not. So why do you defend the analogous expression "a greatest common divisor"?
Yes, I would call myself an oldest sibling. That's implied by calling myself one of two "oldest siblings". In fact, in discussions of birth order, I've called myself a firstborn.
There are many terms in math that slightly deviate from ordinary uses. We use "if" in a slightly twisted way, saying that "if pigs fly, then the moon is made of green cheese" is true. We use "or" in a slightly twisted way, making it always inclusive rather than expressing alternatives. We use "rectangle" in a slightly twisted way, so that a square is a rectangle. We use "multiple" in a slightly twisted way, calling a number a multiple of itself, and we can even "multiply" a number and make it smaller. We extend definitions, making "fraction" no longer mean only a part of something (improper fractions). I'm probably missing the best examples, but you should get the idea. Math is in the habit of stretching the language.
But if you can't accept this as a slight stretch, just call it an idiom. English has enough of those that we should all be used to apparent illogic.
In any case, your "great common denominator" is completely unacceptable.