Theorem opnssneib 14324

Description: Any superset of an open set is a neighborhood of it. (Contributed by NM, 14-Feb-2007.)

Hypothesis

Ref	Expression
neips.1	|- X = U. J

Assertion

Ref	Expression
opnssneib	|- ( ( J e. Top /\ S e. J /\ N C_ X ) -> ( S C_ N <-> N e. ( ( nei ` J ) ` S ) ) )

Proof of Theorem opnssneib

Dummy variable g is distinct from all other variables.

Step	Hyp	Ref	Expression
1		simplr 528	. . . . . 6 |- ( ( ( S e. J /\ N C_ X ) /\ S C_ N ) -> N C_ X )
2		sseq2 3203	. . . . . . . . . 10 |- ( g = S -> ( S C_ g <-> S C_ S ) )
3		sseq1 3202	. . . . . . . . . 10 |- ( g = S -> ( g C_ N <-> S C_ N ) )
4	2, 3	anbi12d 473	. . . . . . . . 9 |- ( g = S -> ( ( S C_ g /\ g C_ N ) <-> ( S C_ S /\ S C_ N ) ) )
5		ssid 3199	. . . . . . . . . 10 |- S C_ S
6	5	biantrur 303	. . . . . . . . 9 |- ( S C_ N <-> ( S C_ S /\ S C_ N ) )
7	4, 6	bitr4di 198	. . . . . . . 8 |- ( g = S -> ( ( S C_ g /\ g C_ N ) <-> S C_ N ) )
8	7	rspcev 2864	. . . . . . 7 |- ( ( S e. J /\ S C_ N ) -> E. g e. J ( S C_ g /\ g C_ N ) )
9	8	adantlr 477	. . . . . 6 |- ( ( ( S e. J /\ N C_ X ) /\ S C_ N ) -> E. g e. J ( S C_ g /\ g C_ N ) )
10	1, 9	jca 306	. . . . 5 |- ( ( ( S e. J /\ N C_ X ) /\ S C_ N ) -> ( N C_ X /\ E. g e. J ( S C_ g /\ g C_ N ) ) )
11	10	ex 115	. . . 4 |- ( ( S e. J /\ N C_ X ) -> ( S C_ N -> ( N C_ X /\ E. g e. J ( S C_ g /\ g C_ N ) ) ) )
12	11	3adant1 1017	. . 3 |- ( ( J e. Top /\ S e. J /\ N C_ X ) -> ( S C_ N -> ( N C_ X /\ E. g e. J ( S C_ g /\ g C_ N ) ) ) )
13		neips.1	. . . . . 6 |- X = U. J
14	13	eltopss 14177	. . . . 5 |- ( ( J e. Top /\ S e. J ) -> S C_ X )
15	13	isnei 14312	. . . . 5 |- ( ( J e. Top /\ S C_ X ) -> ( N e. ( ( nei ` J ) ` S ) <-> ( N C_ X /\ E. g e. J ( S C_ g /\ g C_ N ) ) ) )
16	14, 15	syldan 282	. . . 4 |- ( ( J e. Top /\ S e. J ) -> ( N e. ( ( nei ` J ) ` S ) <-> ( N C_ X /\ E. g e. J ( S C_ g /\ g C_ N ) ) ) )
17	16	3adant3 1019	. . 3 |- ( ( J e. Top /\ S e. J /\ N C_ X ) -> ( N e. ( ( nei ` J ) ` S ) <-> ( N C_ X /\ E. g e. J ( S C_ g /\ g C_ N ) ) ) )
18	12, 17	sylibrd 169	. 2 |- ( ( J e. Top /\ S e. J /\ N C_ X ) -> ( S C_ N -> N e. ( ( nei ` J ) ` S ) ) )
19		ssnei 14319	. . . 4 |- ( ( J e. Top /\ N e. ( ( nei ` J ) ` S ) ) -> S C_ N )
20	19	ex 115	. . 3 |- ( J e. Top -> ( N e. ( ( nei ` J ) ` S ) -> S C_ N ) )
21	20	3ad2ant1 1020	. 2 |- ( ( J e. Top /\ S e. J /\ N C_ X ) -> ( N e. ( ( nei ` J ) ` S ) -> S C_ N ) )
22	18, 21	impbid 129	1 |- ( ( J e. Top /\ S e. J /\ N C_ X ) -> ( S C_ N <-> N e. ( ( nei ` J ) ` S ) ) )

Syntax hints:   -> wi 4   /\ wa 104   <-> wb 105   /\ w3a 980   = wceq 1364   e. wcel 2164   E.wrex 2473   C_ wss 3153   U.cuni 3835   ` cfv 5254   Topctop 14165   neicnei 14306

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-coll 4144  ax-sep 4147  ax-pow 4203  ax-pr 4238

This theorem depends on definitions:  df-bi 117  df-3an 982  df-tru 1367  df-nf 1472  df-sb 1774  df-eu 2045  df-mo 2046  df-clab 2180  df-cleq 2186  df-clel 2189  df-nfc 2325  df-ral 2477  df-rex 2478  df-reu 2479  df-rab 2481  df-v 2762  df-sbc 2986  df-csb 3081  df-un 3157  df-in 3159  df-ss 3166  df-pw 3603  df-sn 3624  df-pr 3625  df-op 3627  df-uni 3836  df-iun 3914  df-br 4030  df-opab 4091  df-mpt 4092  df-id 4324  df-xp 4665  df-rel 4666  df-cnv 4667  df-co 4668  df-dm 4669  df-rn 4670  df-res 4671  df-ima 4672  df-iota 5215  df-fun 5256  df-fn 5257  df-f 5258  df-f1 5259  df-fo 5260  df-f1o 5261  df-fv 5262  df-top 14166  df-nei 14307

This theorem is referenced by:  neissex  14333