Theorem nfun 3232

Description: Hypothesis builder for union. (Contributed by SF, 2-Jan-2018.)

Hypotheses

Ref	Expression
nfbool.1	|- F/_xA
nfbool.2	|- F/_xB

Assertion

Ref	Expression
nfun	|- F/_x(A u. B)

Proof of Theorem nfun

Step	Hyp	Ref	Expression
1		df-un 3215	. 2 |- (A u. B) = ( ∼ A &ncap ∼ B)
2		nfbool.1	. . . 4 |- F/_xA
3	2	nfcompl 3230	. . 3 |- F/_x ∼ A
4		nfbool.2	. . . 4 |- F/_xB
5	4	nfcompl 3230	. . 3 |- F/_x ∼ B
6	3, 5	nfnin 3229	. 2 |- F/_x( ∼ A &ncap ∼ B)
7	1, 6	nfcxfr 2487	1 |- F/_x(A u. B)

Syntax hints:   F/_wnfc 2477   &ncap cnin 3205   ∼ ccompl 3206   u. cun 3208

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 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

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 2479  df-nin 3212  df-compl 3213  df-un 3215

This theorem is referenced by:  nfsymdif  3234  nfop  4605