FA-40574 / Heap invariants / Member archive

Weak join performs a strict improvement swap without reversing equal keys · case 04

The bounded weak join certificate reports an incorrect swapped.

Member previewVariant 4 · 3 implementations · 7 checks per implementation

Case contract

A weak-heap join receives keys, reverse bits, ancestor i and distinct descendant j. When keys[j]<keys[i], swap these keys and flip only reverse[j]; on equality do nothing. Return resulting keys, reversal bits, swapped status, winning key, changed reversal index, and comparison count.

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 3	`{"bits": [0, 0], "comparisons": 1, "flipped": null, "keys": [3, 3], "swapped": true, "winner_key": 3}`	`{"bits": [0, 0], "comparisons": 1, "flipped": null, "keys": [3, 3], "swapped": false, "winner_key": 3}`	Failed

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This record includes three runnable implementations, regression fixtures, execution results, and source hashes.

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