| bin-heap-inv(gch, lpt), keyset(gch) = gc-heap(lpt, nx), lpt0 = lpt, ¬ dups(nx), ∀ n. n ∈ nx → n < # lpt ∧ lpt[n].flags = LP_GROUP_NODES ⊦ ⟪persistence_gc_heap_add_log#(; nx, lpt, gch)⟫ (nx = [] ∧ bin-heap-inv(gch, lpt) ∧ keyset(gch) = gc-heap(lpt, nx) ∧ id-idx(lpt0, lpt)) |