Metamath Proof Explorer


Theorem pnfged

Description: Plus infinity is an upper bound for extended reals. (Contributed by Glauco Siliprandi, 5-Feb-2022)

Ref Expression
Hypothesis pnfged.1 φA*
Assertion pnfged φA+∞

Proof

Step Hyp Ref Expression
1 pnfged.1 φA*
2 pnfge A*A+∞
3 1 2 syl φA+∞