Theorem biorfd

Description: A wff is equivalent to its disjunction with falsehood, deduction form. (Contributed by Peter Mazsa, 22-Aug-2023)

	Ref	Expression
Hypothesis	biorfd.1	|- ( ph -> -. ps )
Assertion	biorfd	|- ( ph -> ( ch <-> ( ps \/ ch ) ) )

Proof

Step	Hyp	Ref	Expression
1		biorfd.1	|- ( ph -> -. ps )
2		biorf	|- ( -. ps -> ( ch <-> ( ps \/ ch ) ) )
3	1 2	syl	|- ( ph -> ( ch <-> ( ps \/ ch ) ) )