FA-40110 / Heap invariants / Member archive

Fibonacci cut preserves the promoted subtree without absorbing its former parent · case 05

The bounded fibonacci cut certificate reports an incorrect descendants.

Member previewVariant 5 · 3 implementations · 7 checks per implementation

Case contract

A Fibonacci cut certificate has child c, parent p, ordered parent children, root ids, parent degree, child mark, and node keys. Cut detaches c, promotes it to the end of roots, clears its mark and parent, and decrements parent degree; it does not erase descendants.

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 2	`{"child_parent": null, "degree": 2, "descendants": [], "mark": false, "parent_children": [1, 3], "root_append": [9, 8, 2]}`	`{"child_parent": null, "degree": 2, "descendants": [4, 5], "mark": false, "parent_children": [1, 3], "root_append": [9, 8, 2]}`	Failed

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