Theorem sb1 1172

Description: One direction of a simplified definition of substitution.

Assertion

Ref	Expression
sb1	|- ([y / x]ph -> E.x(x = y /\ ph))

Proof of Theorem sb1

Step	Hyp	Ref	Expression
1		df-sb 1168	. 2 |- ([y / x]ph <-> ((x = y -> ph) /\ E.x(x = y /\ ph)))
2	1	pm3.27bi 326	1 |- ([y / x]ph -> E.x(x = y /\ ph))

Syntax hints:   -> wi 3   /\ wa 223   = wceq 953  E.wex 977  [wsbc 1166

This theorem is referenced by:  sbf 1182  hbs1f 1185  sbied 1191  sb4a 1195  sb4e 1199  sb4 1218  sbn 1226  sb5rf 1254

This theorem was proved from axioms:  ax-1 4  ax-2 5  ax-3 6  ax-mp 7

This theorem depends on definitions:  df-bi 147  df-an 225  df-sb 1168

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