Metamath Proof Explorer


Theorem nn0xnn0d

Description: A standard nonnegative integer is an extended nonnegative integer, deduction form. (Contributed by AV, 10-Dec-2020)

Ref Expression
Hypothesis nn0xnn0d.1 φ A 0
Assertion nn0xnn0d φ A 0 *

Proof

Step Hyp Ref Expression
1 nn0xnn0d.1 φ A 0
2 nn0ssxnn0 0 0 *
3 2 1 sselid φ A 0 *