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 φ A *
Assertion pnfged φ A +∞

Proof

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