Description: From the union of two functions that agree on the domain overlap, either component can be recovered by restriction. (Contributed by Mario Carneiro, 16-Feb-2015)
Ref | Expression | ||
---|---|---|---|
Assertion | fresaunres1 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | uncom | |
|
2 | 1 | reseq1i | |
3 | incom | |
|
4 | 3 | reseq2i | |
5 | 3 | reseq2i | |
6 | 4 5 | eqeq12i | |
7 | eqcom | |
|
8 | 6 7 | bitri | |
9 | fresaunres2 | |
|
10 | 9 | 3com12 | |
11 | 8 10 | syl3an3b | |
12 | 2 11 | eqtrid | |