Theorem abnexg 6964

Description: Sufficient condition for a class abstraction to be a proper class. The class F can be thought of as an expression in x and the abstraction appearing in the statement as the class of values F as x varies through A. Assuming the antecedents, if that class is a set, then so is the "domain" A. The converse holds without antecedent, see abrexexg 7140. Note that the second antecedent A. x e. A x e. F cannot be translated to A C_ F since F may depend on x. In applications, one may take F = { x } or F = ~P x (see snnex 6966 and pwnex 6968 respectively, proved from abnex 6965, which is a consequence of abnexg 6964 with A = _V). (Contributed by BJ, 2-Dec-2021.)

Assertion

Ref	Expression
abnexg	|- ( A. x e. A ( F e. V /\ x e. F ) -> ( { y | E. x e. A y = F } e. W -> A e. _V ) )

Distinct variable groups:   x, A, y   y, F

Allowed substitution hints:   F( x)   V( x, y)   W( x, y)

Proof of Theorem abnexg

Step	Hyp	Ref	Expression
1		uniexg 6955	. 2 |- ( { y | E. x e. A y = F } e. W -> U. { y | E. x e. A y = F } e. _V )
2		simpl 473	. . . . 5 |- ( ( F e. V /\ x e. F ) -> F e. V )
3	2	ralimi 2952	. . . 4 |- ( A. x e. A ( F e. V /\ x e. F ) -> A. x e. A F e. V )
4		dfiun2g 4552	. . . . . 6 |- ( A. x e. A F e. V -> U_ x e. A F = U. { y | E. x e. A y = F } )
5	4	eleq1d 2686	. . . . 5 |- ( A. x e. A F e. V -> ( U_ x e. A F e. _V <-> U. { y | E. x e. A y = F } e. _V ) )
6	5	biimprd 238	. . . 4 |- ( A. x e. A F e. V -> ( U. { y | E. x e. A y = F } e. _V -> U_ x e. A F e. _V ) )
7	3, 6	syl 17	. . 3 |- ( A. x e. A ( F e. V /\ x e. F ) -> ( U. { y | E. x e. A y = F } e. _V -> U_ x e. A F e. _V ) )
8		simpr 477	. . . . 5 |- ( ( F e. V /\ x e. F ) -> x e. F )
9	8	ralimi 2952	. . . 4 |- ( A. x e. A ( F e. V /\ x e. F ) -> A. x e. A x e. F )
10		iunid 4575	. . . . 5 |- U_ x e. A { x } = A
11		snssi 4339	. . . . . . 7 |- ( x e. F -> { x } C_ F )
12	11	ralimi 2952	. . . . . 6 |- ( A. x e. A x e. F -> A. x e. A { x } C_ F )
13		ss2iun 4536	. . . . . 6 |- ( A. x e. A { x } C_ F -> U_ x e. A { x } C_ U_ x e. A F )
14	12, 13	syl 17	. . . . 5 |- ( A. x e. A x e. F -> U_ x e. A { x } C_ U_ x e. A F )
15	10, 14	syl5eqssr 3650	. . . 4 |- ( A. x e. A x e. F -> A C_ U_ x e. A F )
16		ssexg 4804	. . . . 5 |- ( ( A C_ U_ x e. A F /\ U_ x e. A F e. _V ) -> A e. _V )
17	16	ex 450	. . . 4 |- ( A C_ U_ x e. A F -> ( U_ x e. A F e. _V -> A e. _V ) )
18	9, 15, 17	3syl 18	. . 3 |- ( A. x e. A ( F e. V /\ x e. F ) -> ( U_ x e. A F e. _V -> A e. _V ) )
19	7, 18	syld 47	. 2 |- ( A. x e. A ( F e. V /\ x e. F ) -> ( U. { y | E. x e. A y = F } e. _V -> A e. _V ) )
20	1, 19	syl5 34	1 |- ( A. x e. A ( F e. V /\ x e. F ) -> ( { y | E. x e. A y = F } e. W -> A e. _V ) )

Syntax hints:   -> wi 4   /\ wa 384   = wceq 1483   e. wcel 1990   {cab 2608   A.wral 2912   E.wrex 2913   _Vcvv 3200   C_ wss 3574   {csn 4177   U.cuni 4436   U_ciun 4520

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1722  ax-4 1737  ax-5 1839  ax-6 1888  ax-7 1935  ax-8 1992  ax-9 1999  ax-10 2019  ax-11 2034  ax-12 2047  ax-13 2246  ax-ext 2602  ax-sep 4781  ax-un 6949

This theorem depends on definitions:  df-bi 197  df-or 385  df-an 386  df-3an 1039  df-tru 1486  df-ex 1705  df-nf 1710  df-sb 1881  df-clab 2609  df-cleq 2615  df-clel 2618  df-nfc 2753  df-ral 2917  df-rex 2918  df-v 3202  df-in 3581  df-ss 3588  df-sn 4178  df-uni 4437  df-iun 4522

This theorem is referenced by:  abnex  6965