Talk:Order theory

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== "<" or ">" as Order relations ==

Why are "≤" or "≥" used in the article's definition(s)? Regarding two 2 ordered things, one is less than the other, or vice versa. And it's nonsense to ask if something is less or more than itself. — Preceding unsigned comment added by 108.41.98.105 (talk) 19:06, 4 January 2023 (UTC)

:For total orders, it doesn't make a lot of difference which of these one uses. It is traditional to use ≤ for partial orders and < for (strict) weak orders; I don't know why. But for preorders, the = part of the ≤ relation is not equality, so in that case it is necessary to use ≤, to distinguish the case of two distinct elements that are both ≤ each other from the case of two incomparable elements. —David Eppstein (talk) 19:23, 4 January 2023 (UTC)