Metamath Proof Explorer


Theorem pjoml2

Description: Variation of orthomodular law. Definition in Kalmbach p. 22. (Contributed by NM, 13-Jun-2006) (New usage is discouraged.)

Ref Expression
Assertion pjoml2 A C B C A B A A B = B

Proof

Step Hyp Ref Expression
1 sseq1 A = if A C A 0 A B if A C A 0 B
2 id A = if A C A 0 A = if A C A 0
3 fveq2 A = if A C A 0 A = if A C A 0
4 3 ineq1d A = if A C A 0 A B = if A C A 0 B
5 2 4 oveq12d A = if A C A 0 A A B = if A C A 0 if A C A 0 B
6 5 eqeq1d A = if A C A 0 A A B = B if A C A 0 if A C A 0 B = B
7 1 6 imbi12d A = if A C A 0 A B A A B = B if A C A 0 B if A C A 0 if A C A 0 B = B
8 sseq2 B = if B C B 0 if A C A 0 B if A C A 0 if B C B 0
9 ineq2 B = if B C B 0 if A C A 0 B = if A C A 0 if B C B 0
10 9 oveq2d B = if B C B 0 if A C A 0 if A C A 0 B = if A C A 0 if A C A 0 if B C B 0
11 id B = if B C B 0 B = if B C B 0
12 10 11 eqeq12d B = if B C B 0 if A C A 0 if A C A 0 B = B if A C A 0 if A C A 0 if B C B 0 = if B C B 0
13 8 12 imbi12d B = if B C B 0 if A C A 0 B if A C A 0 if A C A 0 B = B if A C A 0 if B C B 0 if A C A 0 if A C A 0 if B C B 0 = if B C B 0
14 h0elch 0 C
15 14 elimel if A C A 0 C
16 14 elimel if B C B 0 C
17 15 16 pjoml2i if A C A 0 if B C B 0 if A C A 0 if A C A 0 if B C B 0 = if B C B 0
18 7 13 17 dedth2h A C B C A B A A B = B
19 18 3impia A C B C A B A A B = B