Metamath Proof Explorer


Theorem nnnn0d

Description: A positive integer is a nonnegative integer. (Contributed by Mario Carneiro, 27-May-2016)

Ref Expression
Hypothesis nnnn0d.1 φ A
Assertion nnnn0d φ A 0

Proof

Step Hyp Ref Expression
1 nnnn0d.1 φ A
2 nnssnn0 0
3 2 1 sseldi φ A 0