Theorem sbcex 3060

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 3052	. 2 |- ( [. A / x ]. ph <-> A e. { x | ph } )
2		elex 2833	. 2 |- ( A e. { x | ph } -> A e. _V )
3	1, 2	sylbi 121	1 |- ( [. A / x ]. ph -> A e. _V )

Syntax hints:   -> wi 4   e. wcel 2209   {cab 2224   _Vcvv 2821   [.wsbc 3051

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-5 1500  ax-gen 1502  ax-ie1 1546  ax-ie2 1547  ax-8 1557  ax-4 1563  ax-17 1579  ax-i9 1583  ax-ial 1587  ax-ext 2220

This theorem depends on definitions:  df-bi 117  df-sb 1816  df-clab 2225  df-cleq 2231  df-clel 2234  df-v 2823  df-sbc 3052

This theorem is referenced by:  sbcco  3073  sbc5  3075  sbcan  3094  sbcor  3096  sbcn1  3099  sbcim1  3100  sbcbi1  3101  sbcal  3103  sbcex2  3105  sbcel1v  3114  sbcel21v  3116  sbcimdv  3117  sbcrext  3129  spesbc  3138  csbprc  3571  opelopabsb  4397