**Description:** Obsolete version of vtoclg as of 20-Apr-2024. (Contributed by NM, 17-Apr-1995) (New usage is discouraged.)
(Proof modification is discouraged.)

Ref | Expression | ||
---|---|---|---|

Hypotheses | vtoclgOLD.1 | $${\u22a2}{x}={A}\to \left({\phi}\leftrightarrow {\psi}\right)$$ | |

vtoclgOLD.2 | $${\u22a2}{\phi}$$ | ||

Assertion | vtoclgOLD | $${\u22a2}{A}\in {V}\to {\psi}$$ |

Step | Hyp | Ref | Expression |
---|---|---|---|

1 | vtoclgOLD.1 | $${\u22a2}{x}={A}\to \left({\phi}\leftrightarrow {\psi}\right)$$ | |

2 | vtoclgOLD.2 | $${\u22a2}{\phi}$$ | |

3 | nfv | $${\u22a2}\u2132{x}\phantom{\rule{.4em}{0ex}}{\psi}$$ | |

4 | 3 1 2 | vtoclg1f | $${\u22a2}{A}\in {V}\to {\psi}$$ |