| ⊦ btree-sub-clean(r, n, zh) → ( btree-sub-clean(r, n + 1, zh) ↔ ¬ zh[r].leaf ∧ n < zh[r].usedsize ∧ zh[r].zbranches[n].branch? ∧ zh[r].zbranches[n].child ∈ zh → ¬ zh[zh[r].zbranches[n].child].dirty) |
btree-sub-clean(r, n, zh) ⊦ btree-sub-clean(r, n + 1, zh) ↔ ¬ zh[r].leaf ∧ n < zh[r].usedsize ∧ zh[r].zbranches[n].branch? ∧ zh[r].zbranches[n].child ∈ zh → ¬ zh[zh[r].zbranches[n].child].dirty