Description: Inclusion of an intersection of two classes. (Contributed by NM, 30-Oct-2014)
Ref | Expression | ||
---|---|---|---|
Assertion | inss | |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssinss1 | |
|
2 | incom | |
|
3 | ssinss1 | |
|
4 | 2 3 | eqsstrid | |
5 | 1 4 | jaoi | |