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 A B B


Step Hyp Ref Expression
1 incom B A = A B
2 inss1 B A B
3 1 2 eqsstrri A B B