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FA-44606 / Data systems / Open access

Zip unnest exposes flattened output offsets as list ordinals · case 01

Zip unnest exposes flattened output offsets as list ordinals.

Verified by executionVariant 1 · 7 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

zip-list-unnest: Zip unnest exposes flattened output offsets as list ordinals.

THE FAILURE

zip-list-unnest: Zip unnest exposes flattened output offsets as list ordinals.

Unsuccessful approach: One-based ordinals still violate the per-parent zero-based contract.

Case contract

Zip two optional lists within each parent row using longest-list semantics and zero-based ordinals. Missing positions become None; two empty or null lists yield one outer placeholder with ordinal None.

Why this case matters

A bounded deterministic data engine model makes representation and changelog faults reproducible.

1 / The failure

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(d):
    try:
        out=[]
        for ident,left,right in d:
            left=[] if left is None else left
            right=[] if right is None else right
            size=max(len(left),len(right))
            if size==0: out.append([ident,None,None,None])
            for i in range(size):
                a=left[i] if i<len(left) else None
                b=right[i] if i<len(right) else None
                out.append([ident,len(out),a,b])
        return out
    except (IndexError, KeyError, ValueError, StopIteration) as exc:
        return {"representation_error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('longer left', solve([[1, [2, 3], [4]]]), [[1, 0, 2, 4], [1, 1, 3, None]])
    check('longer right', solve([[1, [2], [3, 4]]]), [[1, 0, 2, 3], [1, 1, None, 4]])
    check('empty both', solve([[1, [], None]]), [[1, None, None, None]])
    check('null left', solve([[1, None, [2]]]), [[1, 0, None, 2]])
    check('parent ordinal reset', solve([[1, [1], []], [2, [None], [3]]]), [[1, 0, 1, None], [2, 0, None, 3]])
    check('empty relation', solve([]), [])
    check('null right', solve([[1, [2], None]]), [[1, 0, 2, None]])
elif N == 2:
    check('longer left', solve([[2, [3, 4], [5]]]), [[2, 0, 3, 5], [2, 1, 4, None]])
    check('longer right', solve([[2, [3], [4, 5]]]), [[2, 0, 3, 4], [2, 1, None, 5]])
    check('empty both', solve([[2, [], None]]), [[2, None, None, None]])
    check('null left', solve([[2, None, [3]]]), [[2, 0, None, 3]])
    check('parent ordinal reset', solve([[2, [2], []], [3, [None], [4]]]), [[2, 0, 2, None], [3, 0, None, 4]])
    check('empty relation', solve([]), [])
    check('null right', solve([[2, [3], None]]), [[2, 0, 3, None]])
elif N == 3:
    check('longer left', solve([[3, [4, 5], [6]]]), [[3, 0, 4, 6], [3, 1, 5, None]])
    check('longer right', solve([[3, [4], [5, 6]]]), [[3, 0, 4, 5], [3, 1, None, 6]])
    check('empty both', solve([[3, [], None]]), [[3, None, None, None]])
    check('null left', solve([[3, None, [4]]]), [[3, 0, None, 4]])
    check('parent ordinal reset', solve([[3, [3], []], [4, [None], [5]]]), [[3, 0, 3, None], [4, 0, None, 5]])
    check('empty relation', solve([]), [])
    check('null right', solve([[3, [4], None]]), [[3, 0, 4, None]])
elif N == 4:
    check('longer left', solve([[4, [5, 6], [7]]]), [[4, 0, 5, 7], [4, 1, 6, None]])
    check('longer right', solve([[4, [5], [6, 7]]]), [[4, 0, 5, 6], [4, 1, None, 7]])
    check('empty both', solve([[4, [], None]]), [[4, None, None, None]])
    check('null left', solve([[4, None, [5]]]), [[4, 0, None, 5]])
    check('parent ordinal reset', solve([[4, [4], []], [5, [None], [6]]]), [[4, 0, 4, None], [5, 0, None, 6]])
    check('empty relation', solve([]), [])
    check('null right', solve([[4, [5], None]]), [[4, 0, 5, None]])
elif N == 5:
    check('longer left', solve([[5, [6, 7], [8]]]), [[5, 0, 6, 8], [5, 1, 7, None]])
    check('longer right', solve([[5, [6], [7, 8]]]), [[5, 0, 6, 7], [5, 1, None, 8]])
    check('empty both', solve([[5, [], None]]), [[5, None, None, None]])
    check('null left', solve([[5, None, [6]]]), [[5, 0, None, 6]])
    check('parent ordinal reset', solve([[5, [5], []], [6, [None], [7]]]), [[5, 0, 5, None], [6, 0, None, 7]])
    check('empty relation', solve([]), [])
    check('null right', solve([[5, [6], None]]), [[5, 0, 6, None]])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
longer left[[1, 0, 2, 4], [1, 1, 3, None]][[1, 0, 2, 4], [1, 1, 3, None]]Passed
longer right[[1, 0, 2, 3], [1, 1, None, 4]][[1, 0, 2, 3], [1, 1, None, 4]]Passed
empty both[[1, None, None, None]][[1, None, None, None]]Passed
null left[[1, 0, None, 2]][[1, 0, None, 2]]Passed
parent ordinal reset[[1, 0, 1, None], [2, 1, None, 3]][[1, 0, 1, None], [2, 0, None, 3]]Failed
empty relation[][]Passed
null right[[1, 0, 2, None]][[1, 0, 2, None]]Passed

SHA-256 / 0077f7aa51b9e3331cb9033900d7efd069664b7816504c4c89b0e4a3e426c26b

2 / The unsuccessful fix

Exit 1
"""Failure Map reference implementation. Python standard library only."""
import json

N = 1
observations = []
def solve(d):
    try:
        out=[]
        for ident,left,right in d:
            left=[] if left is None else left
            right=[] if right is None else right
            size=max(len(left),len(right))
            if size==0: out.append([ident,None,None,None])
            for i in range(size):
                a=left[i] if i<len(left) else None
                b=right[i] if i<len(right) else None
                out.append([ident,i+1,a,b])
        return out
    except (IndexError, KeyError, ValueError, StopIteration) as exc:
        return {"representation_error": type(exc).__name__}
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
if N == 1:
    check('longer left', solve([[1, [2, 3], [4]]]), [[1, 0, 2, 4], [1, 1, 3, None]])
    check('longer right', solve([[1, [2], [3, 4]]]), [[1, 0, 2, 3], [1, 1, None, 4]])
    check('empty both', solve([[1, [], None]]), [[1, None, None, None]])
    check('null left', solve([[1, None, [2]]]), [[1, 0, None, 2]])
    check('parent ordinal reset', solve([[1, [1], []], [2, [None], [3]]]), [[1, 0, 1, None], [2, 0, None, 3]])
    check('empty relation', solve([]), [])
    check('null right', solve([[1, [2], None]]), [[1, 0, 2, None]])
elif N == 2:
    check('longer left', solve([[2, [3, 4], [5]]]), [[2, 0, 3, 5], [2, 1, 4, None]])
    check('longer right', solve([[2, [3], [4, 5]]]), [[2, 0, 3, 4], [2, 1, None, 5]])
    check('empty both', solve([[2, [], None]]), [[2, None, None, None]])
    check('null left', solve([[2, None, [3]]]), [[2, 0, None, 3]])
    check('parent ordinal reset', solve([[2, [2], []], [3, [None], [4]]]), [[2, 0, 2, None], [3, 0, None, 4]])
    check('empty relation', solve([]), [])
    check('null right', solve([[2, [3], None]]), [[2, 0, 3, None]])
elif N == 3:
    check('longer left', solve([[3, [4, 5], [6]]]), [[3, 0, 4, 6], [3, 1, 5, None]])
    check('longer right', solve([[3, [4], [5, 6]]]), [[3, 0, 4, 5], [3, 1, None, 6]])
    check('empty both', solve([[3, [], None]]), [[3, None, None, None]])
    check('null left', solve([[3, None, [4]]]), [[3, 0, None, 4]])
    check('parent ordinal reset', solve([[3, [3], []], [4, [None], [5]]]), [[3, 0, 3, None], [4, 0, None, 5]])
    check('empty relation', solve([]), [])
    check('null right', solve([[3, [4], None]]), [[3, 0, 4, None]])
elif N == 4:
    check('longer left', solve([[4, [5, 6], [7]]]), [[4, 0, 5, 7], [4, 1, 6, None]])
    check('longer right', solve([[4, [5], [6, 7]]]), [[4, 0, 5, 6], [4, 1, None, 7]])
    check('empty both', solve([[4, [], None]]), [[4, None, None, None]])
    check('null left', solve([[4, None, [5]]]), [[4, 0, None, 5]])
    check('parent ordinal reset', solve([[4, [4], []], [5, [None], [6]]]), [[4, 0, 4, None], [5, 0, None, 6]])
    check('empty relation', solve([]), [])
    check('null right', solve([[4, [5], None]]), [[4, 0, 5, None]])
elif N == 5:
    check('longer left', solve([[5, [6, 7], [8]]]), [[5, 0, 6, 8], [5, 1, 7, None]])
    check('longer right', solve([[5, [6], [7, 8]]]), [[5, 0, 6, 7], [5, 1, None, 8]])
    check('empty both', solve([[5, [], None]]), [[5, None, None, None]])
    check('null left', solve([[5, None, [6]]]), [[5, 0, None, 6]])
    check('parent ordinal reset', solve([[5, [5], []], [6, [None], [7]]]), [[5, 0, 5, None], [6, 0, None, 7]])
    check('empty relation', solve([]), [])
    check('null right', solve([[5, [6], None]]), [[5, 0, 6, None]])
print(json.dumps({"observations": observations, "passed": all(x["passed"] for x in observations)}, ensure_ascii=False))
raise SystemExit(0 if all(x["passed"] for x in observations) else 1)
Boundary fixtureActualExpectedOutcome
longer left[[1, 1, 2, 4], [1, 2, 3, None]][[1, 0, 2, 4], [1, 1, 3, None]]Failed
longer right[[1, 1, 2, 3], [1, 2, None, 4]][[1, 0, 2, 3], [1, 1, None, 4]]Failed
empty both[[1, None, None, None]][[1, None, None, None]]Passed
null left[[1, 1, None, 2]][[1, 0, None, 2]]Failed
parent ordinal reset[[1, 1, 1, None], [2, 1, None, 3]][[1, 0, 1, None], [2, 0, None, 3]]Failed
empty relation[][]Passed
null right[[1, 1, 2, None]][[1, 0, 2, None]]Failed

SHA-256 / 36046ff872e464a40c4443bed158093a76c85e3af49b613563778248baf7893a

HELD IN THE MEMBER ARCHIVE

The verified repair and its recorded checks are member-only.

This mechanism has 7 recorded checks per implementation. The open-access tier publishes the failure and the unsuccessful fix; the repaired source that passes every check, and the observations that prove it, are available to members.

Every case sharing this mechanism uses the same contract and the same repair, so this one record is held back for all of them.

Member access is invitation-based. Sign in with your invited account to inspect the repair.

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Verification & scope

Offline stipulated semantics over valid small inputs; no performance, concurrency, or production-engine conformance claim. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.

Observations recorded using Python 3.12.14 at 2026-09-29T14:44:13.838976+00:00.

Case digest / 9b521fdf053afbadcf94f0a1453504e64abe3f0142e4e0a54de8a06688a8c158