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Theorem nfth 1350
Description: No variable is (effectively) free in a theorem. (Contributed by Mario Carneiro, 11-Aug-2016.)
Hypothesis
Ref Expression
hbth.1 φ
Assertion
Ref Expression
nfth xφ

Proof of Theorem nfth
StepHypRef Expression
1 hbth.1 . . 3 φ
21hbth 1349 . 2 (φxφ)
32nfi 1348 1 xφ
Colors of variables: wff set class
Syntax hints:  wnf 1346
This theorem was proved from axioms:  ax-1 5  ax-2 6  ax-mp 7  ax-ia1 99  ax-ia2 100  ax-ia3 101  ax-gen 1335
This theorem depends on definitions:  df-bi 110  df-nf 1347
This theorem is referenced by:  nftru  1352  nfequid  1587  sbt  1664  sbc2ie  2823
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