Metamath Proof Explorer


Theorem pprodcnveq

Description: A converse law for parallel product. (Contributed by Scott Fenton, 3-May-2014)

Ref Expression
Assertion pprodcnveq pprodRS=pprodR-1S-1-1

Proof

Step Hyp Ref Expression
1 dfpprod2 pprodRS=1stV×V-1R1stV×V2ndV×V-1S2ndV×V
2 dfpprod2 pprodR-1S-1=1stV×V-1R-11stV×V2ndV×V-1S-12ndV×V
3 2 cnveqi pprodR-1S-1-1=1stV×V-1R-11stV×V2ndV×V-1S-12ndV×V-1
4 cnvin 1stV×V-1R-11stV×V2ndV×V-1S-12ndV×V-1=1stV×V-1R-11stV×V-12ndV×V-1S-12ndV×V-1
5 cnvco1 1stV×V-1R-11stV×V-1=R-11stV×V-11stV×V
6 cnvco1 R-11stV×V-1=1stV×V-1R
7 6 coeq1i R-11stV×V-11stV×V=1stV×V-1R1stV×V
8 coass 1stV×V-1R1stV×V=1stV×V-1R1stV×V
9 5 7 8 3eqtri 1stV×V-1R-11stV×V-1=1stV×V-1R1stV×V
10 cnvco1 2ndV×V-1S-12ndV×V-1=S-12ndV×V-12ndV×V
11 cnvco1 S-12ndV×V-1=2ndV×V-1S
12 11 coeq1i S-12ndV×V-12ndV×V=2ndV×V-1S2ndV×V
13 coass 2ndV×V-1S2ndV×V=2ndV×V-1S2ndV×V
14 10 12 13 3eqtri 2ndV×V-1S-12ndV×V-1=2ndV×V-1S2ndV×V
15 9 14 ineq12i 1stV×V-1R-11stV×V-12ndV×V-1S-12ndV×V-1=1stV×V-1R1stV×V2ndV×V-1S2ndV×V
16 3 4 15 3eqtri pprodR-1S-1-1=1stV×V-1R1stV×V2ndV×V-1S2ndV×V
17 1 16 eqtr4i pprodRS=pprodR-1S-1-1