Theorem olc

Description: Introduction of a disjunct. Axiom *1.3 of WhiteheadRussell p. 96. (Contributed by NM, 30-Aug-1993)

	Ref	Expression
Assertion	olc	⊢ ( 𝜑 → ( 𝜓 ∨ 𝜑 ) )

Proof

Step	Hyp	Ref	Expression
1		ax-1	⊢ ( 𝜑 → ( ¬ 𝜓 → 𝜑 ) )
2	1	orrd	⊢ ( 𝜑 → ( 𝜓 ∨ 𝜑 ) )