FA-41298 / Heap invariants / Member archive

Rank-loss repair preserves unvisited ranks and applies the full local decrease · case 03

The bounded rank loss propagation certificate reports an incorrect prefix ranks.

Member previewVariant 3 · 3 implementations · 7 checks per implementation

Case contract

A stipulated rank-balanced heap repair trace supplies bottom-up nodes [id,stored_rank,left_rank,right_rank], with null child rank -1. Recomputed rank is max child rank if child ranks differ, otherwise child rank+1. A decrease propagates while computed rank is smaller, stopping at first unchanged node. Report local recomputed ranks, decreased ids, stopping id, new prefix ranks, rank drops, and visited count. This models the stated rule only, not every rank-pairing heap variant.

Why this case matters

This isolates an internal heap representation or priority-structure invariant using deterministic finite records.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
regression certificate 4	`{"computed": [1, 2], "decreased": [], "drops": [], "prefix_ranks": [1, 2], "stop": "a", "visited": 1}`	`{"computed": [1, 2], "decreased": [], "drops": [], "prefix_ranks": [1, 5], "stop": "a", "visited": 1}`	Failed

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