| ∀ j0, i1, i0. i→n(j0 - i1) < i→n(i2) → true → (i0 ∈ count-i2j(i1, j0) ↔ i1 ≤ i0 ∧ i0 ≤ j0) ⊦ i0 ∈ count-i2j(i, i2 + i) ↔ i ≤ i0 ∧ i0 ≤ i2 + i |
⊦ i ≤ j → count-i2j(i, j) = count-i2j(i, j - 1) + j
¬ i ≤ i2 + i, ∀ j0, i1, i0. i→n(j0 - i1) < i→n(i2) → true → (i0 ∈ count-i2j(i1, j0) ↔ i1 ≤ i0 ∧ i0 ≤ j0) ⊦ i0 ∈ count-i2j(i, i2 + i) ↔ i ≤ i0 ∧ i0 ≤ i2 + i
i ≤ i2 + i, ∀ j0, i1, i0. i→n(j0 - i1) < i→n(i2) → true → (i0 ∈ count-i2j(i1, j0) ↔ i1 ≤ i0 ∧ i0 ≤ j0) ⊦ i0 ∈ count-i2j(i, i2 + i - 1) + (i2 + i) ↔ i ≤ i0 ∧ i0 ≤ i2 + i
Used terms: i2 + i, i