Metamath Proof Explorer


Theorem cmdmdi

Description: Commuting subspaces form a dual modular pair. (Contributed by NM, 25-Apr-2006) (New usage is discouraged.)

Ref Expression
Hypotheses sumdmdi.1 AC
sumdmdi.2 BC
Assertion cmdmdi A𝐶BA𝑀*B

Proof

Step Hyp Ref Expression
1 sumdmdi.1 AC
2 sumdmdi.2 BC
3 1 choccli AC
4 2 choccli BC
5 3 4 cmmdi A𝐶BA𝑀B
6 1 2 cmcm4i A𝐶BA𝐶B
7 dmdmd ACBCA𝑀*BA𝑀B
8 1 2 7 mp2an A𝑀*BA𝑀B
9 5 6 8 3imtr4i A𝐶BA𝑀*B