Theorem mpoxopovel

Description: Element of the value of an operation given by a maps-to rule, where the first argument is a pair and the base set of the second argument is the first component of the first argument. (Contributed by Alexander van der Vekens and Mario Carneiro, 10-Oct-2017)

	Ref	Expression
Hypothesis	mpoxopoveq.f	|- F = ( x e. _V , y e. ( 1st ` x ) |-> { n e. ( 1st ` x ) | ph } )
Assertion	mpoxopovel	|- ( ( V e. X /\ W e. Y ) -> ( N e. ( <. V , W >. F K ) <-> ( K e. V /\ N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) ) )

Proof

Step	Hyp	Ref	Expression
1		mpoxopoveq.f	|- F = ( x e. _V , y e. ( 1st ` x ) |-> { n e. ( 1st ` x ) | ph } )
2	1	mpoxopn0yelv	|- ( ( V e. X /\ W e. Y ) -> ( N e. ( <. V , W >. F K ) -> K e. V ) )
3	2	pm4.71rd	|- ( ( V e. X /\ W e. Y ) -> ( N e. ( <. V , W >. F K ) <-> ( K e. V /\ N e. ( <. V , W >. F K ) ) ) )
4	1	mpoxopoveq	|- ( ( ( V e. X /\ W e. Y ) /\ K e. V ) -> ( <. V , W >. F K ) = { n e. V | [. <. V , W >. / x ]. [. K / y ]. ph } )
5	4	eleq2d	|- ( ( ( V e. X /\ W e. Y ) /\ K e. V ) -> ( N e. ( <. V , W >. F K ) <-> N e. { n e. V | [. <. V , W >. / x ]. [. K / y ]. ph } ) )
6		nfcv	|- F/_ n V
7	6	elrabsf	|- ( N e. { n e. V | [. <. V , W >. / x ]. [. K / y ]. ph } <-> ( N e. V /\ [. N / n ]. [. <. V , W >. / x ]. [. K / y ]. ph ) )
8		sbccom	|- ( [. N / n ]. [. <. V , W >. / x ]. [. K / y ]. ph <-> [. <. V , W >. / x ]. [. N / n ]. [. K / y ]. ph )
9		sbccom	|- ( [. N / n ]. [. K / y ]. ph <-> [. K / y ]. [. N / n ]. ph )
10	9	sbcbii	|- ( [. <. V , W >. / x ]. [. N / n ]. [. K / y ]. ph <-> [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph )
11	8 10	bitri	|- ( [. N / n ]. [. <. V , W >. / x ]. [. K / y ]. ph <-> [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph )
12	11	anbi2i	|- ( ( N e. V /\ [. N / n ]. [. <. V , W >. / x ]. [. K / y ]. ph ) <-> ( N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) )
13	7 12	bitri	|- ( N e. { n e. V | [. <. V , W >. / x ]. [. K / y ]. ph } <-> ( N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) )
14	5 13	bitrdi	|- ( ( ( V e. X /\ W e. Y ) /\ K e. V ) -> ( N e. ( <. V , W >. F K ) <-> ( N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) ) )
15	14	pm5.32da	|- ( ( V e. X /\ W e. Y ) -> ( ( K e. V /\ N e. ( <. V , W >. F K ) ) <-> ( K e. V /\ ( N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) ) ) )
16		3anass	|- ( ( K e. V /\ N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) <-> ( K e. V /\ ( N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) ) )
17	15 16	bitr4di	|- ( ( V e. X /\ W e. Y ) -> ( ( K e. V /\ N e. ( <. V , W >. F K ) ) <-> ( K e. V /\ N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) ) )
18	3 17	bitrd	|- ( ( V e. X /\ W e. Y ) -> ( N e. ( <. V , W >. F K ) <-> ( K e. V /\ N e. V /\ [. <. V , W >. / x ]. [. K / y ]. [. N / n ]. ph ) ) )