Theorem el2v1

Description: New way ( elv , and the theorems beginning with "el2v" or "el3v") to shorten some proofs. (Contributed by Peter Mazsa, 23-Oct-2018)

	Ref	Expression
Hypothesis	el2v1.1	$$⊢\left(x\in \mathrm{V}\wedge \phi \right)\to \psi$$
Assertion	el2v1	$$⊢\phi \to \psi$$

Proof

Step	Hyp	Ref	Expression
1		el2v1.1	$$⊢\left(x\in \mathrm{V}\wedge \phi \right)\to \psi$$
2		vex	$$⊢x\in \mathrm{V}$$
3	2 1	mpan	$$⊢\phi \to \psi$$