Commit 2022-05-16 13:42 a9e74ab7

feat(order/filter/at_top_bot): use weaker TC assumptions, add lemmas (#14105)

• add filter.eventually_gt_of_tendsto_at_top, filter.eventually_ne_at_bot, filter.eventually_lt_of_tendsto_at_bot;
• generalize filter.eventually_ne_of_tendsto_at_top and filter.eventually_ne_of_tendsto_at_bot from nontrivial ordered (semi)rings to preorders with no maximal/minimal elements.