**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 | $${\u22a2}{A}\cap {B}\subseteq {B}$$ |

Step | Hyp | Ref | Expression |
---|---|---|---|

1 | incom | $${\u22a2}{B}\cap {A}={A}\cap {B}$$ | |

2 | inss1 | $${\u22a2}{B}\cap {A}\subseteq {B}$$ | |

3 | 1 2 | eqsstrri | $${\u22a2}{A}\cap {B}\subseteq {B}$$ |