eccc472e8d
This PR removes the now unnecessary `set_option grind.warning false` statements, now that the warning is disabled by default.
17 lines
709 B
Text
17 lines
709 B
Text
open List
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example (h : zs <+ ys) (w : xs ++ ys <+ zs) (h' : ¬xs = []) : False := by
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fail_if_success grind
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-- I'm not sure how to make progress here without manually adding that since `xs ≠ []`, it must be a `cons`.
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have : ∃ y ys, xs = y :: ys := match xs, h' with | _ :: _, _ => by simp
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grind (gen := 6)
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example {xs ys zs : List α} (h : zs <+ ys) :
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xs ++ ys <+ zs ↔ xs = [] ∧ ys = zs := by
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constructor
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· intro w
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grind -- stuck, because of the failure of the example above.
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-- An alternative idea would be to argue via inequalities about lengths,
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-- but any grind pattern for `Sublist.length_le` seems to result in an explosion of useless facts.
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· intro w
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grind
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