Theorem cliftetb

Description: show d is the same as an if-else involving a,b. (Contributed by Jarvin Udandy, 20-Sep-2020)

	Ref	Expression
Hypotheses	cliftetb.1	|- ( ( ph /\ ch ) \/ ( ps /\ -. ch ) )
	cliftetb.2	|- th
Assertion	cliftetb	|- ( th <-> ( ( ph /\ ch ) \/ ( ps /\ -. ch ) ) )

Proof

Step	Hyp	Ref	Expression
1		cliftetb.1	|- ( ( ph /\ ch ) \/ ( ps /\ -. ch ) )
2		cliftetb.2	|- th
3	2 1	2th	|- ( th <-> ( ( ph /\ ch ) \/ ( ps /\ -. ch ) ) )