Theorem nfriota 5932

Description: A variable not free in a wff remains so in a restricted iota descriptor. (Contributed by NM, 12-Oct-2011.)

Hypotheses

Ref	Expression
nfriota.1	|- F/ x ph
nfriota.2	|- F/_ x A

Assertion

Ref	Expression
nfriota	|- F/_ x ( iota_ y e. A ph )

Distinct variable group:   x, y

Allowed substitution hints:   ph( x, y)   A( x, y)

Proof of Theorem nfriota

Step	Hyp	Ref	Expression
1		nftru 1490	. . 3 |- F/ y T.
2		nfriota.1	. . . 4 |- F/ x ph
3	2	a1i 9	. . 3 |- ( T. -> F/ x ph )
4		nfriota.2	. . . 4 |- F/_ x A
5	4	a1i 9	. . 3 |- ( T. -> F/_ x A )
6	1, 3, 5	nfriotadxy 5931	. 2 |- ( T. -> F/_ x ( iota_ y e. A ph ) )
7	6	mptru 1382	1 |- F/_ x ( iota_ y e. A ph )

Syntax hints:   T. wtru 1374   F/wnf 1484   F/_wnfc 2337   iota_crio 5921

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 711  ax-5 1471  ax-7 1472  ax-gen 1473  ax-ie1 1517  ax-ie2 1518  ax-8 1528  ax-10 1529  ax-11 1530  ax-i12 1531  ax-bndl 1533  ax-4 1534  ax-17 1550  ax-i9 1554  ax-ial 1558  ax-i5r 1559  ax-ext 2189

This theorem depends on definitions:  df-bi 117  df-tru 1376  df-nf 1485  df-sb 1787  df-clab 2194  df-cleq 2200  df-clel 2203  df-nfc 2339  df-rex 2492  df-sn 3649  df-uni 3865  df-iota 5251  df-riota 5922

This theorem is referenced by:  csbriotag  5935  lble  9055