Metamath Proof Explorer


Theorem 0xnn0

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

Ref Expression
Assertion 0xnn0 0 ∈ ℕ0*

Proof

Step Hyp Ref Expression
1 nn0ssxnn0 0 ⊆ ℕ0*
2 0nn0 0 ∈ ℕ0
3 1 2 sselii 0 ∈ ℕ0*