Description: Taking images under a one-to-one function preserves subsets. (Contributed by Stefan O'Rear, 30-Oct-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | f1imass | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | simplrl | |
|
2 | 1 | sseld | |
3 | simplr | |
|
4 | 3 | sseld | |
5 | simplll | |
|
6 | simpr | |
|
7 | simp1rl | |
|
8 | 7 | 3expa | |
9 | f1elima | |
|
10 | 5 6 8 9 | syl3anc | |
11 | simp1rr | |
|
12 | 11 | 3expa | |
13 | f1elima | |
|
14 | 5 6 12 13 | syl3anc | |
15 | 4 10 14 | 3imtr3d | |
16 | 15 | ex | |
17 | 2 16 | syld | |
18 | 17 | pm2.43d | |
19 | 18 | ssrdv | |
20 | 19 | ex | |
21 | imass2 | |
|
22 | 20 21 | impbid1 | |