Description: Subclass theorem for the classes of cosets by A and B . (Contributed by Peter Mazsa, 11-Nov-2019)
Ref | Expression | ||
---|---|---|---|
Assertion | cossss |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssbr | ||
2 | ssbr | ||
3 | 1 2 | anim12d | |
4 | 3 | eximdv | |
5 | 4 | ssopab2dv | |
6 | df-coss | ||
7 | df-coss | ||
8 | 5 6 7 | 3sstr4g |