| ⊦ valid-indices(ar, ar.indicesWhere(φ)) |
⊦ valid-indices(ar, nx) ↔ (∀ n. n ∈ nx → n < # ar)
⊦ n ∈ ar.indicesWhere(φ) ↔ n < # ar ∧ φ(ar[n])
Used simplifier rules: indices-where-in: ⊦ n ∈ ar.indicesWhere(φ) ↔ n < # ar ∧ φ(ar[n]); Used terms: ar.indicesWhere(φ), ar