Description: The double union of a relation is its field. (Contributed by NM, 17-Sep-2006)
Ref | Expression | ||
---|---|---|---|
Assertion | relfld | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | relssdmrn | |
|
2 | uniss | |
|
3 | uniss | |
|
4 | 1 2 3 | 3syl | |
5 | unixpss | |
|
6 | 4 5 | sstrdi | |
7 | dmrnssfld | |
|
8 | 7 | a1i | |
9 | 6 8 | eqssd | |