Description: A converse law for parallel product. (Contributed by Scott Fenton, 3-May-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | pprodcnveq | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | dfpprod2 | |
|
2 | dfpprod2 | |
|
3 | 2 | cnveqi | |
4 | cnvin | |
|
5 | cnvco1 | |
|
6 | cnvco1 | |
|
7 | 6 | coeq1i | |
8 | coass | |
|
9 | 5 7 8 | 3eqtri | |
10 | cnvco1 | |
|
11 | cnvco1 | |
|
12 | 11 | coeq1i | |
13 | coass | |
|
14 | 10 12 13 | 3eqtri | |
15 | 9 14 | ineq12i | |
16 | 3 4 15 | 3eqtri | |
17 | 1 16 | eqtr4i | |