| j0 < i, is_arrayref(r, i, st), 0 ≤ j0, 0 < i ⊦ j0 = j, r -- j0 ' ∈ st |
⊦ is_arrayref(r, i, st) ↔ (∀ j. 0 ≤ j ∧ j < i → r -- j ' ∈ st)
j0 < i, ∀ j. 0 ≤ j ∧ j < i → r -- j ' ∈ st, 0 ≤ j0, 0 < i ⊦ j0 = j, r -- j0 ' ∈ st
[[CONCRETESIMPRULES : ()], [EXTRATERMS : (st, i, r)]]