lean4-htt/tests/lean/run/specialize2.lean
Leonardo de Moura bbe6d37109 fix: specialize
2021-09-11 19:52:51 -07:00

11 lines
320 B
Text
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

example : (p → q → False) ↔ (¬ p ¬ q) := by
apply Iff.intro
. intro h
byCases hp:p <;> byCases hq:q
. specialize h hp hq; contradiction
. exact Or.inr hq
. exact Or.inl hp
. exact Or.inr hq
. intro
| Or.inl hnp => intros; contradiction
| Or.inr hnq => intros; contradiction