Theorem exss 4256

Description: Restricted existence in a class (even if proper) implies restricted existence in a subset. (Contributed by NM, 23-Aug-2003.)

Assertion

Ref	Expression
exss	|- ( E. x e. A ph -> E. y ( y C_ A /\ E. x e. y ph ) )

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

Allowed substitution hint:   ph( x)

Proof of Theorem exss

Dummy variables z w are mutually distinct and distinct from all other variables.

Step	Hyp	Ref	Expression
1		rabn0m 3474	. . 3 |- ( E. z z e. { x e. A | ph } <-> E. x e. A ph )
2		df-rab 2481	. . . . 5 |- { x e. A | ph } = { x | ( x e. A /\ ph ) }
3	2	eleq2i 2260	. . . 4 |- ( z e. { x e. A | ph } <-> z e. { x | ( x e. A /\ ph ) } )
4	3	exbii 1616	. . 3 |- ( E. z z e. { x e. A | ph } <-> E. z z e. { x | ( x e. A /\ ph ) } )
5	1, 4	bitr3i 186	. 2 |- ( E. x e. A ph <-> E. z z e. { x | ( x e. A /\ ph ) } )
6		vex 2763	. . . . . 6 |- z e. _V
7	6	snss 3753	. . . . 5 |- ( z e. { x | ( x e. A /\ ph ) } <-> { z } C_ { x | ( x e. A /\ ph ) } )
8		ssab2 3263	. . . . . 6 |- { x | ( x e. A /\ ph ) } C_ A
9		sstr2 3186	. . . . . 6 |- ( { z } C_ { x | ( x e. A /\ ph ) } -> ( { x | ( x e. A /\ ph ) } C_ A -> { z } C_ A ) )
10	8, 9	mpi 15	. . . . 5 |- ( { z } C_ { x | ( x e. A /\ ph ) } -> { z } C_ A )
11	7, 10	sylbi 121	. . . 4 |- ( z e. { x | ( x e. A /\ ph ) } -> { z } C_ A )
12		simpr 110	. . . . . . . 8 |- ( ( [ z / x ] x e. A /\ [ z / x ] ph ) -> [ z / x ] ph )
13		equsb1 1796	. . . . . . . . 9 |- [ z / x ] x = z
14		velsn 3635	. . . . . . . . . 10 |- ( x e. { z } <-> x = z )
15	14	sbbii 1776	. . . . . . . . 9 |- ( [ z / x ] x e. { z } <-> [ z / x ] x = z )
16	13, 15	mpbir 146	. . . . . . . 8 |- [ z / x ] x e. { z }
17	12, 16	jctil 312	. . . . . . 7 |- ( ( [ z / x ] x e. A /\ [ z / x ] ph ) -> ( [ z / x ] x e. { z } /\ [ z / x ] ph ) )
18		df-clab 2180	. . . . . . . 8 |- ( z e. { x | ( x e. A /\ ph ) } <-> [ z / x ] ( x e. A /\ ph ) )
19		sban 1971	. . . . . . . 8 |- ( [ z / x ] ( x e. A /\ ph ) <-> ( [ z / x ] x e. A /\ [ z / x ] ph ) )
20	18, 19	bitri 184	. . . . . . 7 |- ( z e. { x | ( x e. A /\ ph ) } <-> ( [ z / x ] x e. A /\ [ z / x ] ph ) )
21		df-rab 2481	. . . . . . . . 9 |- { x e. { z } | ph } = { x | ( x e. { z } /\ ph ) }
22	21	eleq2i 2260	. . . . . . . 8 |- ( z e. { x e. { z } | ph } <-> z e. { x | ( x e. { z } /\ ph ) } )
23		df-clab 2180	. . . . . . . . 9 |- ( z e. { x | ( x e. { z } /\ ph ) } <-> [ z / x ] ( x e. { z } /\ ph ) )
24		sban 1971	. . . . . . . . 9 |- ( [ z / x ] ( x e. { z } /\ ph ) <-> ( [ z / x ] x e. { z } /\ [ z / x ] ph ) )
25	23, 24	bitri 184	. . . . . . . 8 |- ( z e. { x | ( x e. { z } /\ ph ) } <-> ( [ z / x ] x e. { z } /\ [ z / x ] ph ) )
26	22, 25	bitri 184	. . . . . . 7 |- ( z e. { x e. { z } | ph } <-> ( [ z / x ] x e. { z } /\ [ z / x ] ph ) )
27	17, 20, 26	3imtr4i 201	. . . . . 6 |- ( z e. { x | ( x e. A /\ ph ) } -> z e. { x e. { z } | ph } )
28		elex2 2776	. . . . . 6 |- ( z e. { x e. { z } | ph } -> E. w w e. { x e. { z } | ph } )
29	27, 28	syl 14	. . . . 5 |- ( z e. { x | ( x e. A /\ ph ) } -> E. w w e. { x e. { z } | ph } )
30		rabn0m 3474	. . . . 5 |- ( E. w w e. { x e. { z } | ph } <-> E. x e. { z } ph )
31	29, 30	sylib 122	. . . 4 |- ( z e. { x | ( x e. A /\ ph ) } -> E. x e. { z } ph )
32	6	snex 4214	. . . . 5 |- { z } e. _V
33		sseq1 3202	. . . . . 6 |- ( y = { z } -> ( y C_ A <-> { z } C_ A ) )
34		rexeq 2691	. . . . . 6 |- ( y = { z } -> ( E. x e. y ph <-> E. x e. { z } ph ) )
35	33, 34	anbi12d 473	. . . . 5 |- ( y = { z } -> ( ( y C_ A /\ E. x e. y ph ) <-> ( { z } C_ A /\ E. x e. { z } ph ) ) )
36	32, 35	spcev 2855	. . . 4 |- ( ( { z } C_ A /\ E. x e. { z } ph ) -> E. y ( y C_ A /\ E. x e. y ph ) )
37	11, 31, 36	syl2anc 411	. . 3 |- ( z e. { x | ( x e. A /\ ph ) } -> E. y ( y C_ A /\ E. x e. y ph ) )
38	37	exlimiv 1609	. 2 |- ( E. z z e. { x | ( x e. A /\ ph ) } -> E. y ( y C_ A /\ E. x e. y ph ) )
39	5, 38	sylbi 121	1 |- ( E. x e. A ph -> E. y ( y C_ A /\ E. x e. y ph ) )

Syntax hints:   -> wi 4   /\ wa 104   = wceq 1364   E.wex 1503   [wsb 1773   e. wcel 2164   {cab 2179   E.wrex 2473   {crab 2476   C_ wss 3153   {csn 3618

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 106  ax-ia2 107  ax-ia3 108  ax-io 710  ax-5 1458  ax-7 1459  ax-gen 1460  ax-ie1 1504  ax-ie2 1505  ax-8 1515  ax-10 1516  ax-11 1517  ax-i12 1518  ax-bndl 1520  ax-4 1521  ax-17 1537  ax-i9 1541  ax-ial 1545  ax-i5r 1546  ax-14 2167  ax-ext 2175  ax-sep 4147  ax-pow 4203

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1472  df-sb 1774  df-clab 2180  df-cleq 2186  df-clel 2189  df-nfc 2325  df-rex 2478  df-rab 2481  df-v 2762  df-in 3159  df-ss 3166  df-pw 3603  df-sn 3624

This theorem is referenced by: (None)