Theorem nfs1f 2124

Description: If is not free in , it is not free in . (Contributed by Mario Carneiro, 11-Aug-2016.)

Hypothesis

Ref	Expression
nfs1f.1

Assertion

Ref	Expression
nfs1f

Proof of Theorem nfs1f

Step	Hyp	Ref	Expression
1		nfs1f.1	. . 3
2	1	sbf 2121	. 2
3	2, 1	nfxfr 1645	1

Syntax hints:  F/wnf 1616  [wsb 1739

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1618  ax-4 1631  ax-5 1704  ax-6 1747  ax-7 1790  ax-10 1837  ax-12 1854  ax-13 1999

This theorem depends on definitions:  df-bi 185  df-an 371  df-ex 1613  df-nf 1617  df-sb 1740