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Metamath Proof Explorer

Definition df-vd1

Description: Definition of virtual deduction. (Contributed by Alan Sare, 21-Apr-2011) (New usage is discouraged.)

		Ref	Expression
	Assertion	df-vd1	$⊢ (φ \to ψ) \leftrightarrow (φ \to ψ)$

Step	Hyp	Ref	Expression
0		wph	$wff φ$
1		wps	$wff ψ$
2	0 1	wvd1	$wff (φ \to ψ)$
3	0 1	wi	$wff (φ \to ψ)$
4	2 3	wb	$wff ((φ \to ψ) \leftrightarrow (φ \to ψ))$