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Metamath Proof Explorer


Theorem rspsbca

Description: Restricted quantifier version of Axiom 4 of Mendelson p. 69. (Contributed by NM, 14-Dec-2005)

Ref Expression
Assertion rspsbca A B x B φ [˙A / x]˙ φ

Proof

Step Hyp Ref Expression
1 rspsbc A B x B φ [˙A / x]˙ φ
2 1 imp A B x B φ [˙A / x]˙ φ