refactor: define List.IsChain, deprecate Chain and Chain'
#1052
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Mathlib CI status (docs):
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fgdorais
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awaiting-review
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I'm not a fan, this turns things that would be recursive on lists into well founded recursions. |
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What about renaming |
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BTW, what things start using well founded recursions with my def? |
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I'm partial to |
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My main motivation is that we get |
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What's wrong with using |
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| /-- Recursion principle for `List.IsChain. -/ | ||
| @[elab_as_elim] | ||
| protected def IsChain.rec {p : ∀ l : List α, IsChain R l → Sort u} |
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Please use motive instead of p.
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Maybe add recOn for convenience? I'm not sure if casesOn would be useful but it doesn't hurt to have it.
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| /-- Induction principle for `List.IsChain. -/ | ||
| @[elab_as_elim] | ||
| protected theorem IsChain.induction {p : ∀ l : List α, IsChain R l → Prop} |
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| theorem IsChain.imp_of_mem (hRS : ∀ a ∈ l, ∀ b ∈ l, R a b → S a b) (h : IsChain R l) : | ||
| IsChain S l := by | ||
| induction l with |
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Wouldn't this be simpler using IsChain.rec?
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I would like to merge this sooner than later. It looks like there's just a few small issues and a Mathlib adaptation. |
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I'm sorry for the delay. I'll have some time to work on this tomorrow. |
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Umm, I this PR still active? |
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