FAILURE MAP
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FA-46376 / Bounded deques / Open access

Block split aliases both halves to the same block identity · case 01

Block split aliases both halves to the same block identity.

Verified by executionVariant 1 · 6 checks per implementationDownload source bundle ↓JSON ↗

ROOT CAUSE

Block split aliases both halves to the same block identity.

THE FAILURE

Block split aliases both halves to the same block identity.

Unsuccessful approach: The partial repair still applies the incorrect transition to an admitted boundary or multi-element case.

Case contract

Split a deque storage block at an interior cut, keeping the original identity on the left and assigning a fresh right identity. Publish an incremented directory epoch and ordered block IDs without changing total element count.

Why this case matters

Controlled bounded deque implementation model with explicit storage and lifecycle observations.

1 / The failure

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

N = 1
observations = []
def solve(x):
    a,cut,old,fresh,epoch=x
    left=a[:cut]
    right=a[cut:]
    left_id=old
    right_id=old
    version=epoch+1
    size=len(left)+len(right)
    directory=[left_id,right_id]
    return [left,right,left_id,right_id,version,size,directory]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([[N,N+1,N+2,N+3],2,8,9,3]), {1: [[1, 2], [3, 4], 8, 9, 4, 4, [8, 9]], 2: [[2, 3], [4, 5], 8, 9, 4, 4, [8, 9]], 3: [[3, 4], [5, 6], 8, 9, 4, 4, [8, 9]], 4: [[4, 5], [6, 7], 8, 9, 4, 4, [8, 9]], 5: [[5, 6], [7, 8], 8, 9, 4, 4, [8, 9]]}[N])
check('1', solve([[N,N+1,N+2],1,2,4,0]), {1: [[1], [2, 3], 2, 4, 1, 3, [2, 4]], 2: [[2], [3, 4], 2, 4, 1, 3, [2, 4]], 3: [[3], [4, 5], 2, 4, 1, 3, [2, 4]], 4: [[4], [5, 6], 2, 4, 1, 3, [2, 4]], 5: [[5], [6, 7], 2, 4, 1, 3, [2, 4]]}[N])
check('2', solve([[N,N+1],1,7,11,5]), {1: [[1], [2], 7, 11, 6, 2, [7, 11]], 2: [[2], [3], 7, 11, 6, 2, [7, 11]], 3: [[3], [4], 7, 11, 6, 2, [7, 11]], 4: [[4], [5], 7, 11, 6, 2, [7, 11]], 5: [[5], [6], 7, 11, 6, 2, [7, 11]]}[N])
check('3', solve([[N,N+1,N+2,N+3,N+4],3,12,13,4]), {1: [[1, 2, 3], [4, 5], 12, 13, 5, 5, [12, 13]], 2: [[2, 3, 4], [5, 6], 12, 13, 5, 5, [12, 13]], 3: [[3, 4, 5], [6, 7], 12, 13, 5, 5, [12, 13]], 4: [[4, 5, 6], [7, 8], 12, 13, 5, 5, [12, 13]], 5: [[5, 6, 7], [8, 9], 12, 13, 5, 5, [12, 13]]}[N])
check('4', solve([[N,N+1,N+2,N+3],1,3,8,2]), {1: [[1], [2, 3, 4], 3, 8, 3, 4, [3, 8]], 2: [[2], [3, 4, 5], 3, 8, 3, 4, [3, 8]], 3: [[3], [4, 5, 6], 3, 8, 3, 4, [3, 8]], 4: [[4], [5, 6, 7], 3, 8, 3, 4, [3, 8]], 5: [[5], [6, 7, 8], 3, 8, 3, 4, [3, 8]]}[N])
check('5', solve([[N,N+1,N+2,N+3,N+4],4,5,6,8]), {1: [[1, 2, 3, 4], [5], 5, 6, 9, 5, [5, 6]], 2: [[2, 3, 4, 5], [6], 5, 6, 9, 5, [5, 6]], 3: [[3, 4, 5, 6], [7], 5, 6, 9, 5, [5, 6]], 4: [[4, 5, 6, 7], [8], 5, 6, 9, 5, [5, 6]], 5: [[5, 6, 7, 8], [9], 5, 6, 9, 5, [5, 6]]}[N])
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
0[[1, 2], [3, 4], 8, 8, 4, 4, [8, 8]][[1, 2], [3, 4], 8, 9, 4, 4, [8, 9]]Failed
1[[1], [2, 3], 2, 2, 1, 3, [2, 2]][[1], [2, 3], 2, 4, 1, 3, [2, 4]]Failed
2[[1], [2], 7, 7, 6, 2, [7, 7]][[1], [2], 7, 11, 6, 2, [7, 11]]Failed
3[[1, 2, 3], [4, 5], 12, 12, 5, 5, [12, 12]][[1, 2, 3], [4, 5], 12, 13, 5, 5, [12, 13]]Failed
4[[1], [2, 3, 4], 3, 3, 3, 4, [3, 3]][[1], [2, 3, 4], 3, 8, 3, 4, [3, 8]]Failed
5[[1, 2, 3, 4], [5], 5, 5, 9, 5, [5, 5]][[1, 2, 3, 4], [5], 5, 6, 9, 5, [5, 6]]Failed

SHA-256 / 38f3ef835aeea09f7e36537a2808171d837ea3a7e9e4f2b4e8284d0e09c05c41

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(x):
    a,cut,old,fresh,epoch=x
    left=a[:cut]
    right=a[cut:]
    left_id=old
    right_id=fresh if cut==1 else old
    version=epoch+1
    size=len(left)+len(right)
    directory=[left_id,right_id]
    return [left,right,left_id,right_id,version,size,directory]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('0', solve([[N,N+1,N+2,N+3],2,8,9,3]), {1: [[1, 2], [3, 4], 8, 9, 4, 4, [8, 9]], 2: [[2, 3], [4, 5], 8, 9, 4, 4, [8, 9]], 3: [[3, 4], [5, 6], 8, 9, 4, 4, [8, 9]], 4: [[4, 5], [6, 7], 8, 9, 4, 4, [8, 9]], 5: [[5, 6], [7, 8], 8, 9, 4, 4, [8, 9]]}[N])
check('1', solve([[N,N+1,N+2],1,2,4,0]), {1: [[1], [2, 3], 2, 4, 1, 3, [2, 4]], 2: [[2], [3, 4], 2, 4, 1, 3, [2, 4]], 3: [[3], [4, 5], 2, 4, 1, 3, [2, 4]], 4: [[4], [5, 6], 2, 4, 1, 3, [2, 4]], 5: [[5], [6, 7], 2, 4, 1, 3, [2, 4]]}[N])
check('2', solve([[N,N+1],1,7,11,5]), {1: [[1], [2], 7, 11, 6, 2, [7, 11]], 2: [[2], [3], 7, 11, 6, 2, [7, 11]], 3: [[3], [4], 7, 11, 6, 2, [7, 11]], 4: [[4], [5], 7, 11, 6, 2, [7, 11]], 5: [[5], [6], 7, 11, 6, 2, [7, 11]]}[N])
check('3', solve([[N,N+1,N+2,N+3,N+4],3,12,13,4]), {1: [[1, 2, 3], [4, 5], 12, 13, 5, 5, [12, 13]], 2: [[2, 3, 4], [5, 6], 12, 13, 5, 5, [12, 13]], 3: [[3, 4, 5], [6, 7], 12, 13, 5, 5, [12, 13]], 4: [[4, 5, 6], [7, 8], 12, 13, 5, 5, [12, 13]], 5: [[5, 6, 7], [8, 9], 12, 13, 5, 5, [12, 13]]}[N])
check('4', solve([[N,N+1,N+2,N+3],1,3,8,2]), {1: [[1], [2, 3, 4], 3, 8, 3, 4, [3, 8]], 2: [[2], [3, 4, 5], 3, 8, 3, 4, [3, 8]], 3: [[3], [4, 5, 6], 3, 8, 3, 4, [3, 8]], 4: [[4], [5, 6, 7], 3, 8, 3, 4, [3, 8]], 5: [[5], [6, 7, 8], 3, 8, 3, 4, [3, 8]]}[N])
check('5', solve([[N,N+1,N+2,N+3,N+4],4,5,6,8]), {1: [[1, 2, 3, 4], [5], 5, 6, 9, 5, [5, 6]], 2: [[2, 3, 4, 5], [6], 5, 6, 9, 5, [5, 6]], 3: [[3, 4, 5, 6], [7], 5, 6, 9, 5, [5, 6]], 4: [[4, 5, 6, 7], [8], 5, 6, 9, 5, [5, 6]], 5: [[5, 6, 7, 8], [9], 5, 6, 9, 5, [5, 6]]}[N])
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
0[[1, 2], [3, 4], 8, 8, 4, 4, [8, 8]][[1, 2], [3, 4], 8, 9, 4, 4, [8, 9]]Failed
1[[1], [2, 3], 2, 4, 1, 3, [2, 4]][[1], [2, 3], 2, 4, 1, 3, [2, 4]]Passed
2[[1], [2], 7, 11, 6, 2, [7, 11]][[1], [2], 7, 11, 6, 2, [7, 11]]Passed
3[[1, 2, 3], [4, 5], 12, 12, 5, 5, [12, 12]][[1, 2, 3], [4, 5], 12, 13, 5, 5, [12, 13]]Failed
4[[1], [2, 3, 4], 3, 8, 3, 4, [3, 8]][[1], [2, 3, 4], 3, 8, 3, 4, [3, 8]]Passed
5[[1, 2, 3, 4], [5], 5, 5, 9, 5, [5, 5]][[1, 2, 3, 4], [5], 5, 6, 9, 5, [5, 6]]Failed

SHA-256 / 4538d4e9046379b02d2d9c2f5ae0f4acb88e2a44acf7aaa8ffa9580d858fface

HELD IN THE MEMBER ARCHIVE

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

This mechanism has 6 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.

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Verification & scope

Offline finite deterministic model; no claim of production implementation or concurrent memory-model conformance. 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 2026-09-29T14:44:31.608993+00:00.

Case digest / 7426293d80073d836678dccecf7739edec76c39d7cab5957e8eb9caf0b2a1e81