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Theorem sbbibvv 2363
Description: Reversal of substitution. (Contributed by AV, 6-Aug-2023.)
Assertion
Ref Expression
sbbibvv (∀𝑦([𝑦 / 𝑥]𝜑𝜓) ↔ ∀𝑥(𝜑 ↔ [𝑥 / 𝑦]𝜓))
Distinct variable groups:   𝜓,𝑥   𝜑,𝑦   𝑥,𝑦
Allowed substitution hints:   𝜑(𝑥)   𝜓(𝑦)

Proof of Theorem sbbibvv
StepHypRef Expression
1 nfv 1912 . 2 𝑦𝜑
2 nfv 1912 . 2 𝑥𝜓
31, 2sbbib 2362 1 (∀𝑦([𝑦 / 𝑥]𝜑𝜓) ↔ ∀𝑥(𝜑 ↔ [𝑥 / 𝑦]𝜓))
Colors of variables: wff setvar class
Syntax hints:  wb 206  wal 1535  [wsb 2062
This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8  ax-gen 1792  ax-4 1806  ax-5 1908  ax-6 1965  ax-7 2005  ax-10 2139  ax-11 2155  ax-12 2175
This theorem depends on definitions:  df-bi 207  df-an 396  df-or 848  df-tru 1540  df-ex 1777  df-nf 1781  df-sb 2063
This theorem is referenced by: (None)
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