Description: Associative law for the restriction of a composition. (Contributed by NM, 12-Dec-2006)
Ref | Expression | ||
---|---|---|---|
Assertion | resco | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | relres | |
|
2 | relco | |
|
3 | vex | |
|
4 | vex | |
|
5 | 3 4 | brco | |
6 | 5 | anbi2i | |
7 | 19.42v | |
|
8 | vex | |
|
9 | 8 | brresi | |
10 | 9 | anbi1i | |
11 | anass | |
|
12 | 10 11 | bitr2i | |
13 | 12 | exbii | |
14 | 6 7 13 | 3bitr2i | |
15 | 4 | brresi | |
16 | 3 4 | brco | |
17 | 14 15 16 | 3bitr4i | |
18 | 1 2 17 | eqbrriv | |