Theorem ninexg 4097

Description: The anti-intersection of two sets is a set. (Contributed by SF, 12-Jan-2015.)

Assertion

Ref	Expression
ninexg	|- ((A e. V /\ B e. W) -> (A &ncap B) e. _V)

Proof of Theorem ninexg

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

Step	Hyp	Ref	Expression
1		nineq1 3234	. . 3 |- (x = A -> (x &ncap y) = (A &ncap y))
2	1	eleq1d 2419	. 2 |- (x = A -> ((x &ncap y) e. _V <-> (A &ncap y) e. _V))
3		nineq2 3235	. . 3 |- (y = B -> (A &ncap y) = (A &ncap B))
4	3	eleq1d 2419	. 2 |- (y = B -> ((A &ncap y) e. _V <-> (A &ncap B) e. _V))
5		ax-nin 4078	. . 3 |- E.zA.w(w e. z <-> (w e. x -/\ w e. y))
6		isset 2863	. . . 4 |- ((x &ncap y) e. _V <-> E.z z = (x &ncap y))
7		dfcleq 2347	. . . . . 6 |- (z = (x &ncap y) <-> A.w(w e. z <-> w e. (x &ncap y)))
8		vex 2862	. . . . . . . . 9 |- w e. _V
9	8	elnin 3224	. . . . . . . 8 |- (w e. (x &ncap y) <-> (w e. x -/\ w e. y))
10	9	bibi2i 304	. . . . . . 7 |- ((w e. z <-> w e. (x &ncap y)) <-> (w e. z <-> (w e. x -/\ w e. y)))
11	10	albii 1566	. . . . . 6 |- (A.w(w e. z <-> w e. (x &ncap y)) <-> A.w(w e. z <-> (w e. x -/\ w e. y)))
12	7, 11	bitri 240	. . . . 5 |- (z = (x &ncap y) <-> A.w(w e. z <-> (w e. x -/\ w e. y)))
13	12	exbii 1582	. . . 4 |- (E.z z = (x &ncap y) <-> E.zA.w(w e. z <-> (w e. x -/\ w e. y)))
14	6, 13	bitri 240	. . 3 |- ((x &ncap y) e. _V <-> E.zA.w(w e. z <-> (w e. x -/\ w e. y)))
15	5, 14	mpbir 200	. 2 |- (x &ncap y) e. _V
16	2, 4, 15	vtocl2g 2918	1 |- ((A e. V /\ B e. W) -> (A &ncap B) e. _V)

Syntax hints:   -> wi 4   <-> wb 176   /\ wa 358   -/\ wnan 1287  A.wal 1540  E.wex 1541   = wceq 1642   e. wcel 1710  _Vcvv 2859   &ncap cnin 3204

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-3 7  ax-mp 8  ax-gen 1546  ax-5 1557  ax-17 1616  ax-9 1654  ax-8 1675  ax-6 1729  ax-7 1734  ax-11 1746  ax-12 1925  ax-ext 2334  ax-nin 4078

This theorem depends on definitions:  df-bi 177  df-or 359  df-an 360  df-nan 1288  df-tru 1319  df-ex 1542  df-nf 1545  df-sb 1649  df-clab 2340  df-cleq 2346  df-clel 2349  df-nfc 2478  df-v 2861  df-nin 3211

This theorem is referenced by:  ninex  4098  complexg  4099  inexg  4100  unexg  4101