Theorem nfun 3099

Description: Bound-variable hypothesis builder for the union of classes. (Contributed by NM, 15-Sep-2003.) (Revised by Mario Carneiro, 14-Oct-2016.)

Hypotheses

Ref	Expression
nfun.1	|- F/_ x A
nfun.2	|- F/_ x B

Assertion

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

Proof of Theorem nfun

Dummy variable y is distinct from all other variables.

Step	Hyp	Ref	Expression
1		df-un 2922	. 2 |- ( A u. B ) = { y | ( y e. A \/ y e. B ) }
2		nfun.1	. . . . 5 |- F/_ x A
3	2	nfcri 2172	. . . 4 |- F/ x y e. A
4		nfun.2	. . . . 5 |- F/_ x B
5	4	nfcri 2172	. . . 4 |- F/ x y e. B
6	3, 5	nfor 1466	. . 3 |- F/ x ( y e. A \/ y e. B )
7	6	nfab 2182	. 2 |- F/_ x { y | ( y e. A \/ y e. B ) }
8	1, 7	nfcxfr 2175	1 |- F/_ x ( A u. B )

Syntax hints:   \/ wo 629   e. wcel 1393   {cab 2026   F/_wnfc 2165   u. cun 2915

This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-io 630  ax-5 1336  ax-7 1337  ax-gen 1338  ax-ie1 1382  ax-ie2 1383  ax-8 1395  ax-10 1396  ax-11 1397  ax-i12 1398  ax-bndl 1399  ax-4 1400  ax-17 1419  ax-i9 1423  ax-ial 1427  ax-i5r 1428  ax-ext 2022

This theorem depends on definitions:  df-bi 110  df-nf 1350  df-sb 1646  df-clab 2027  df-cleq 2033  df-clel 2036  df-nfc 2167  df-un 2922

This theorem is referenced by:  nfsuc  4145