Metamath Proof Explorer


Theorem cgrcoml

Description: Congruence commutes on the left. Biconditional version of Theorem 2.4 of Schwabhauser p. 27. (Contributed by Scott Fenton, 12-Jun-2013)

Ref Expression
Assertion cgrcoml N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N A B Cgr C D B A Cgr C D

Proof

Step Hyp Ref Expression
1 simp1 N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N N
2 simp2l N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N A 𝔼 N
3 simp2r N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N B 𝔼 N
4 1 2 3 cgrrflx2d N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N A B Cgr B A
5 simp3l N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N C 𝔼 N
6 simp3r N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N D 𝔼 N
7 axcgrtr N A 𝔼 N B 𝔼 N B 𝔼 N A 𝔼 N C 𝔼 N D 𝔼 N A B Cgr B A A B Cgr C D B A Cgr C D
8 1 2 3 3 2 5 6 7 syl133anc N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N A B Cgr B A A B Cgr C D B A Cgr C D
9 4 8 mpand N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N A B Cgr C D B A Cgr C D
10 1 3 2 cgrrflx2d N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N B A Cgr A B
11 axcgrtr N B 𝔼 N A 𝔼 N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N B A Cgr A B B A Cgr C D A B Cgr C D
12 1 3 2 2 3 5 6 11 syl133anc N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N B A Cgr A B B A Cgr C D A B Cgr C D
13 10 12 mpand N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N B A Cgr C D A B Cgr C D
14 9 13 impbid N A 𝔼 N B 𝔼 N C 𝔼 N D 𝔼 N A B Cgr C D B A Cgr C D