Theorem ifpfal 1076

Description: Value of the conditional operator for propositions when its first argument is false. Analogue for propositions of iffalse 4490. This is essentially dedlemb 1047. (Contributed by BJ, 20-Sep-2019.) (Proof shortened by Wolf Lammen, 25-Jun-2020.)

Assertion

Ref	Expression
ifpfal	⊢ (¬ 𝜑 → (if-(𝜑, 𝜓, 𝜒) ↔ 𝜒))

Proof of Theorem ifpfal

Step	Hyp	Ref	Expression
1		ifpn 1074	. 2 ⊢ (if-(𝜑, 𝜓, 𝜒) ↔ if-(¬ 𝜑, 𝜒, 𝜓))
2		ifptru 1075	. 2 ⊢ (¬ 𝜑 → (if-(¬ 𝜑, 𝜒, 𝜓) ↔ 𝜒))
3	1, 2	bitrid 283	1 ⊢ (¬ 𝜑 → (if-(𝜑, 𝜓, 𝜒) ↔ 𝜒))

Syntax hints:  ¬ wn 3   → wi 4   ↔ wb 206  if-wif 1063

This theorem was proved from axioms:  ax-mp 5  ax-1 6  ax-2 7  ax-3 8

This theorem depends on definitions:  df-bi 207  df-an 396  df-or 849  df-ifp 1064

This theorem is referenced by:  ifpid  1077  elimh  1083  axprlem3  5374  axpr  5376  axprlem3OLD  5377  axprlem5OLD  5379  wlkdlem4  29775  lfgriswlk  29778  2pthnloop  29822  eupth2lem3lem4  30324  axprALT2  35293  satfv1lem  35584  wl-3xorfal  37754  sn-axprlem3  42619