Description: Any collection of empty sets is disjoint. (Contributed by Mario Carneiro, 14-Nov-2016)
Ref | Expression | ||
---|---|---|---|
Assertion | 0disj | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | 0ss | |
|
2 | 1 | rgenw | |
3 | sndisj | |
|
4 | disjss2 | |
|
5 | 2 3 4 | mp2 | |