Theorem pm5.54 1020

Description: Theorem *5.54 of [WhiteheadRussell] p. 125. (Contributed by NM, 3-Jan-2005.) (Proof shortened by Wolf Lammen, 7-Nov-2013.)

Assertion

Ref	Expression
pm5.54	⊢ (((𝜑 ∧ 𝜓) ↔ 𝜑) ∨ ((𝜑 ∧ 𝜓) ↔ 𝜓))

Proof of Theorem pm5.54

Step	Hyp	Ref	Expression
1		iba 527	. . . . 5 ⊢ (𝜓 → (𝜑 ↔ (𝜑 ∧ 𝜓)))
2	1	bicomd 223	. . . 4 ⊢ (𝜓 → ((𝜑 ∧ 𝜓) ↔ 𝜑))
3	2	adantl 481	. . 3 ⊢ ((𝜑 ∧ 𝜓) → ((𝜑 ∧ 𝜓) ↔ 𝜑))
4	3, 2	pm5.21ni 377	. 2 ⊢ (¬ ((𝜑 ∧ 𝜓) ↔ 𝜑) → ((𝜑 ∧ 𝜓) ↔ 𝜓))
5	4	orri 863	1 ⊢ (((𝜑 ∧ 𝜓) ↔ 𝜑) ∨ ((𝜑 ∧ 𝜓) ↔ 𝜓))

Syntax hints:   ↔ wb 206   ∧ wa 395   ∨ wo 848

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

This theorem is referenced by: (None)