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Theorem alcomiw 1968
Description: Weak version of alcom 2034. Uses only Tarski's FOL axiom schemes. (Contributed by NM, 10-Apr-2017.)
Hypothesis
Ref Expression
alcomiw.1 (𝑦 = 𝑧 → (𝜑𝜓))
Assertion
Ref Expression
alcomiw (∀𝑥𝑦𝜑 → ∀𝑦𝑥𝜑)
Distinct variable groups:   𝑦,𝑧   𝑥,𝑦   𝜑,𝑧   𝜓,𝑦
Allowed substitution hints:   𝜑(𝑥,𝑦)   𝜓(𝑥,𝑧)

Proof of Theorem alcomiw
StepHypRef Expression
1 alcomiw.1 . . . . 5 (𝑦 = 𝑧 → (𝜑𝜓))
21biimpd 219 . . . 4 (𝑦 = 𝑧 → (𝜑𝜓))
32cbvalivw 1931 . . 3 (∀𝑦𝜑 → ∀𝑧𝜓)
43alimi 1736 . 2 (∀𝑥𝑦𝜑 → ∀𝑥𝑧𝜓)
5 ax-5 1836 . 2 (∀𝑥𝑧𝜓 → ∀𝑦𝑥𝑧𝜓)
61biimprd 238 . . . . . 6 (𝑦 = 𝑧 → (𝜓𝜑))
76equcoms 1944 . . . . 5 (𝑧 = 𝑦 → (𝜓𝜑))
87spimvw 1924 . . . 4 (∀𝑧𝜓𝜑)
98alimi 1736 . . 3 (∀𝑥𝑧𝜓 → ∀𝑥𝜑)
109alimi 1736 . 2 (∀𝑦𝑥𝑧𝜓 → ∀𝑦𝑥𝜑)
114, 5, 103syl 18 1 (∀𝑥𝑦𝜑 → ∀𝑦𝑥𝜑)
Colors of variables: wff setvar class
Syntax hints:  wi 4  wb 196  wal 1478
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1719  ax-4 1734  ax-5 1836  ax-6 1885  ax-7 1932
This theorem depends on definitions:  df-bi 197  df-an 386  df-ex 1702
This theorem is referenced by:  hbalw  1974  ax11w  2004  bj-ssblem2  32308
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