Theorem imsym1

Description: A symmetry with -> .

See negsym1 for more information. (Contributed by Anthony Hart, 4-Sep-2011)

	Ref	Expression
Assertion	imsym1	|- ( ( ps -> ( ps -> F. ) ) -> ( ps -> ph ) )

Proof

Step	Hyp	Ref	Expression
1		pm2.21	|- ( -. ps -> ( ps -> ph ) )
2		falim	|- ( F. -> ph )
3	2	imim2i	|- ( ( ps -> F. ) -> ( ps -> ph ) )
4	1 3	ja	|- ( ( ps -> ( ps -> F. ) ) -> ( ps -> ph ) )