Metamath Proof Explorer


Theorem inss2

Description: The intersection of two classes is a subset of one of them. Part of Exercise 12 of TakeutiZaring p. 18. (Contributed by NM, 27-Apr-1994)

Ref Expression
Assertion inss2 ABB

Proof

Step Hyp Ref Expression
1 incom BA=AB
2 inss1 BAB
3 1 2 eqsstrri ABB