728980443f
as suggested by @semorrison in https://leanprover.zulipchat.com/#narrow/stream/116290-rss/topic/cleanDecreasingBy/near/462659021 Follow-up to #5016.
69 lines
1.4 KiB
Text
69 lines
1.4 KiB
Text
/--
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error: tactic 'fail' failed
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x y : Nat
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⊢ x - 1 < x
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-/
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#guard_msgs in
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def g (x : Nat) (y : Nat) : Nat := g (x - 1) y
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termination_by x
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decreasing_by fail
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/--
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error: tactic 'fail' failed
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x : List Nat
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y : Nat
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⊢ sizeOf x.tail < sizeOf x
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-/
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#guard_msgs in
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def h (x : List Nat) (y : Nat) : Nat := h x.tail y
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termination_by x
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decreasing_by fail
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/--
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error: tactic 'fail' failed
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x : List Nat
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y : Nat
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⊢ x.tail.length < x.length
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-/
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#guard_msgs in
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def f (x : List Nat) (y : Nat) : Nat := f x.tail y
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termination_by x.length
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decreasing_by fail
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/--
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error: tactic 'fail' failed
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x : List Nat
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y : Nat
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⊢ x.tail.length < x.length
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-/
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#guard_msgs in
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mutual
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def f1 (x : List Nat) (y : Nat) : Nat := f2 x.tail y
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termination_by x.length
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decreasing_by fail
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def f2 (x : List Nat) (y : Nat) : Nat := f1 x.tail y
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termination_by x.length
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decreasing_by fail
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end
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/--
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error: tactic 'fail' failed
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x : List Nat
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y : Nat
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⊢ (invImage
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(fun x =>
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PSum.casesOn x (fun _x => PSigma.casesOn _x fun x y => x.length) fun _x =>
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PSigma.casesOn _x fun x y => x.length)
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instWellFoundedRelationOfSizeOf).1
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(PSum.inr ⟨x.tail, y⟩) (PSum.inl ⟨x, y⟩)
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-/
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#guard_msgs in
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set_option debug.rawDecreasingByGoal true in
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mutual
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def g1 (x : List Nat) (y : Nat) : Nat := g2 x.tail y
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termination_by x.length
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decreasing_by fail
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def g2 (x : List Nat) (y : Nat) : Nat := g1 x.tail y
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termination_by x.length
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decreasing_by fail
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end
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