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Theorem hbal 2033
Description: If 𝑥 is not free in 𝜑, it is not free in 𝑦𝜑. (Contributed by NM, 12-Mar-1993.)
Hypothesis
Ref Expression
hbal.1 (𝜑 → ∀𝑥𝜑)
Assertion
Ref Expression
hbal (∀𝑦𝜑 → ∀𝑥𝑦𝜑)

Proof of Theorem hbal
StepHypRef Expression
1 hbal.1 . . 3 (𝜑 → ∀𝑥𝜑)
21alimi 1736 . 2 (∀𝑦𝜑 → ∀𝑦𝑥𝜑)
3 ax-11 2031 . 2 (∀𝑦𝑥𝜑 → ∀𝑥𝑦𝜑)
42, 3syl 17 1 (∀𝑦𝜑 → ∀𝑥𝑦𝜑)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wal 1478
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-gen 1719  ax-4 1734  ax-11 2031
This theorem is referenced by:  hbexOLD  2149  nfal  2150  cbv3hvOLD  2172  hbral  2939  wl-nfalv  32983
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