Metamath Proof Explorer


Theorem ecres

Description: Restricted coset of B . (Contributed by Peter Mazsa, 9-Dec-2018)

Ref Expression
Assertion ecres B R A = x | B A B R x

Proof

Step Hyp Ref Expression
1 elecres x V x B R A B A B R x
2 1 elv x B R A B A B R x
3 2 abbi2i B R A = x | B A B R x