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Description: Increasing an element of a half-open range of nonnegative integers by 1 results in an element of the half-open range of nonnegative integers with an upper bound increased by 1. (Contributed by Alexander van der Vekens, 1-Aug-2018) (Proof shortened by Thierry Arnoux, 14-Dec-2023)
| Ref | Expression | ||
|---|---|---|---|
| Assertion | elfzom1p1elfzo | ⊢ ( ( 𝑁 ∈ ℕ ∧ 𝑋 ∈ ( 0 ..^ ( 𝑁 − 1 ) ) ) → ( 𝑋 + 1 ) ∈ ( 0 ..^ 𝑁 ) ) |
| Step | Hyp | Ref | Expression |
|---|---|---|---|
| 1 | nnz | ⊢ ( 𝑁 ∈ ℕ → 𝑁 ∈ ℤ ) | |
| 2 | elfzom1elp1fzo | ⊢ ( ( 𝑁 ∈ ℤ ∧ 𝑋 ∈ ( 0 ..^ ( 𝑁 − 1 ) ) ) → ( 𝑋 + 1 ) ∈ ( 0 ..^ 𝑁 ) ) | |
| 3 | 1 2 | sylan | ⊢ ( ( 𝑁 ∈ ℕ ∧ 𝑋 ∈ ( 0 ..^ ( 𝑁 − 1 ) ) ) → ( 𝑋 + 1 ) ∈ ( 0 ..^ 𝑁 ) ) |