Metamath Proof Explorer


Theorem chpsscon3

Description: Hilbert lattice contraposition law for strict ordering. (Contributed by NM, 12-Jun-2004) (New usage is discouraged.)

Ref Expression
Assertion chpsscon3 A C B C A B B A

Proof

Step Hyp Ref Expression
1 chsscon3 A C B C A B B A
2 chsscon3 B C A C B A A B
3 2 ancoms A C B C B A A B
4 3 notbid A C B C ¬ B A ¬ A B
5 1 4 anbi12d A C B C A B ¬ B A B A ¬ A B
6 dfpss3 A B A B ¬ B A
7 dfpss3 B A B A ¬ A B
8 5 6 7 3bitr4g A C B C A B B A