Metamath Proof Explorer


Theorem nn0xnn0

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

Ref Expression
Assertion nn0xnn0 A 0 A 0 *

Proof

Step Hyp Ref Expression
1 nn0ssxnn0 0 0 *
2 1 sseli A 0 A 0 *