Theorem noror

Description: \/ is expressible via -\/ . (Contributed by Remi, 26-Oct-2023) (Proof shortened by Wolf Lammen, 8-Dec-2023)

	Ref	Expression
Assertion	noror	|- ( ( ph \/ ps ) <-> ( ( ph -\/ ps ) -\/ ( ph -\/ ps ) ) )

Proof

Step	Hyp	Ref	Expression
1		df-nor	|- ( ( ph -\/ ps ) <-> -. ( ph \/ ps ) )
2	1	con2bii	|- ( ( ph \/ ps ) <-> -. ( ph -\/ ps ) )
3		nornot	|- ( -. ( ph -\/ ps ) <-> ( ( ph -\/ ps ) -\/ ( ph -\/ ps ) ) )
4	2 3	bitri	|- ( ( ph \/ ps ) <-> ( ( ph -\/ ps ) -\/ ( ph -\/ ps ) ) )