Theorem pm2.45 228

Description: Theorem *2.45 of [WhiteheadRussell] p. 106.

Assertion

Ref	Expression
pm2.45	⊢ (¬ (φ ∨ ψ) → ¬ φ)

Proof of Theorem pm2.45

Step	Hyp	Ref	Expression
1		orc 225	. 2 ⊢ (φ → (φ ∨ ψ))
2	1	con3i 90	1 ⊢ (¬ (φ ∨ ψ) → ¬ φ)

Syntax hints:  ¬ wn 1   → wi 2   ∨ wo 195

This theorem is referenced by:  eueq3 1430

This theorem was proved from axioms:  ax-1 3  ax-2 4  ax-3 5  ax-mp 6

This theorem depends on definitions:  df-bi 128  df-or 197

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