Metamath Proof Explorer


Theorem iinssf

Description: Subset implication for an indexed intersection. (Contributed by Glauco Siliprandi, 23-Oct-2021)

Ref Expression
Hypothesis iinssf.1 _xC
Assertion iinssf xABCxABC

Proof

Step Hyp Ref Expression
1 iinssf.1 _xC
2 eliin yVyxABxAyB
3 2 elv yxABxAyB
4 ssel BCyByC
5 4 reximi xABCxAyByC
6 1 nfcri xyC
7 6 r19.36vf xAyByCxAyByC
8 5 7 syl xABCxAyByC
9 3 8 biimtrid xABCyxAByC
10 9 ssrdv xABCxABC