Description: Equality theorem for class union. Exercise 15 of TakeutiZaring p. 18. (Contributed by NM, 10-Aug-1993) (Proof shortened by Andrew Salmon, 29-Jun-2011) (Proof shortened by BJ, 13-Apr-2024)
Ref | Expression | ||
---|---|---|---|
Assertion | unieq | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | eqimss | |
|
2 | 1 | unissd | |
3 | eqimss2 | |
|
4 | 3 | unissd | |
5 | 2 4 | eqssd | |