Description: The standard nonnegative integers are a subset of the extended nonnegative integers. (Contributed by AV, 10-Dec-2020)
Ref | Expression | ||
---|---|---|---|
Assertion | nn0ssxnn0 | ⊢ ℕ0 ⊆ ℕ0* |
Step | Hyp | Ref | Expression |
---|---|---|---|
1 | ssun1 | ⊢ ℕ0 ⊆ ( ℕ0 ∪ { +∞ } ) | |
2 | df-xnn0 | ⊢ ℕ0* = ( ℕ0 ∪ { +∞ } ) | |
3 | 1 2 | sseqtrri | ⊢ ℕ0 ⊆ ℕ0* |