4d58a3d124
This PR unifies various ways of naming auxiliary declarations in a conflict-free way and ensures the method is compatible with diverging branches of elaboration such as parallelism or Aesop-like backtracking+replaying search.
18 lines
661 B
Text
18 lines
661 B
Text
open scoped Classical
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/--
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error: tactic 'native_decide' failed, could not evaluate decidable instance. Error: (interpreter) unknown declaration 'ohno._nativeDecide_1_1'
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---
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error: failed to compile definition, consider marking it as 'noncomputable' because it depends on 'Classical.propDecidable', which is 'noncomputable'
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-/
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#guard_msgs in
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theorem ohno : False := by
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let f : Nat → Nat := fun n => if n=0 then 0 else
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if (∃ k, n = 2 * k) then n / 2 else 3 * n + 1;
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have h2 : f (f 2) ≠ 4 := by
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native_decide;
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have h2 : f (f 2) = 4 := by
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have : ∃ k, 2 = 2 * k := ⟨1, rfl⟩
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simp +decide +arith [f, this];
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omega
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contradiction
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