Theorem sbcex 2963

Description: By our definition of proper substitution, it can only be true if the substituted expression is a set. (Contributed by Mario Carneiro, 13-Oct-2016.)

Assertion

Ref	Expression
sbcex	|- ( [. A / x ]. ph -> A e. _V )

Proof of Theorem sbcex

Step	Hyp	Ref	Expression
1		df-sbc 2956	. 2 |- ( [. A / x ]. ph <-> A e. { x | ph } )
2		elex 2741	. 2 |- ( A e. { x | ph } -> A e. _V )
3	1, 2	sylbi 120	1 |- ( [. A / x ]. ph -> A e. _V )

Syntax hints:   -> wi 4   e. wcel 2141   {cab 2156   _Vcvv 2730   [.wsbc 2955

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-ia1 105  ax-ia2 106  ax-ia3 107  ax-5 1440  ax-gen 1442  ax-ie1 1486  ax-ie2 1487  ax-8 1497  ax-4 1503  ax-17 1519  ax-i9 1523  ax-ial 1527  ax-ext 2152

This theorem depends on definitions:  df-bi 116  df-sb 1756  df-clab 2157  df-cleq 2163  df-clel 2166  df-v 2732  df-sbc 2956

This theorem is referenced by:  sbcco  2976  sbc5  2978  sbcan  2997  sbcor  2999  sbcn1  3002  sbcim1  3003  sbcbi1  3004  sbcal  3006  sbcex2  3008  sbcel1v  3017  sbcel21v  3019  sbcimdv  3020  sbcrext  3032  spesbc  3040  csbprc  3460  opelopabsb  4245