Description: The union of the successor of a set is equal to the binary union of that set with its union. (Contributed by NM, 30-Aug-1993) Extract from unisuc . (Revised by BJ, 28-Dec-2024)
Ref | Expression | ||
---|---|---|---|
Assertion | unisucs |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | df-suc | ||
2 | 1 | unieqi | |
3 | 2 | a1i | |
4 | uniun | ||
5 | 4 | a1i | |
6 | unisng | ||
7 | 6 | uneq2d | |
8 | 3 5 7 | 3eqtrd |