Theorem nfriota 5887

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 1480	. . 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 5886	. 2 |- ( T. -> F/_ x ( iota_ y e. A ph ) )
7	6	mptru 1373	1 |- F/_ x ( iota_ y e. A ph )

Syntax hints:   T. wtru 1365   F/wnf 1474   F/_wnfc 2326   iota_crio 5876

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 1461  ax-7 1462  ax-gen 1463  ax-ie1 1507  ax-ie2 1508  ax-8 1518  ax-10 1519  ax-11 1520  ax-i12 1521  ax-bndl 1523  ax-4 1524  ax-17 1540  ax-i9 1544  ax-ial 1548  ax-i5r 1549  ax-ext 2178

This theorem depends on definitions:  df-bi 117  df-tru 1367  df-nf 1475  df-sb 1777  df-clab 2183  df-cleq 2189  df-clel 2192  df-nfc 2328  df-rex 2481  df-sn 3628  df-uni 3840  df-iota 5219  df-riota 5877

This theorem is referenced by:  csbriotag  5890  lble  8974