[Merged by Bors] - feat(set_theory/cardinal/cofinality): weaker definition for regular cardinals #14433
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LGTM bors d+ I think this conflicts with other PRs I just borsed |
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…ardinals (#14433) We weaken `c.ord.cof = c` to `c ≤ c.ord.cof` in the definition of regular cardinals, in order to slightly simplify proofs. The lemma `is_regular.cof_eq` shows that this leads to an equivalent definition.
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…ardinals (#14433) We weaken `c.ord.cof = c` to `c ≤ c.ord.cof` in the definition of regular cardinals, in order to slightly simplify proofs. The lemma `is_regular.cof_eq` shows that this leads to an equivalent definition.
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We weaken
c.ord.cof = ctoc ≤ c.ord.cofin the definition of regular cardinals, in order to slightly simplify proofs. The lemmais_regular.cof_eqshows that this leads to an equivalent definition.I also golfed
is_regular_succslightly.