Description: Two ways of saying that two classes are disjoint. (Contributed by NM, 19-May-1998)
Ref | Expression | ||
---|---|---|---|
Assertion | disj3 | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | pm4.71 | |
|
2 | eldif | |
|
3 | 2 | bibi2i | |
4 | 1 3 | bitr4i | |
5 | 4 | albii | |
6 | disj1 | |
|
7 | dfcleq | |
|
8 | 5 6 7 | 3bitr4i | |