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FA-100521 / Sparse tensor canonicalization / Open access

Sparse tensor: CSR row-pointer intervals are treated as nonempty row markers · case 01

CSR row-pointer intervals are treated as nonempty row markers.

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

ROOT CAUSE

An empty CSR row is represented by equal adjacent pointers, not a zero-length global array.

THE FAILURE

An empty CSR row is represented by equal adjacent pointers, not a zero-length global array.

Unsuccessful approach: A nonempty row may contain multiple items; emptiness is pointer equality.

Case contract

Return the number of empty rows in a valid CSR row pointer array.

Why this case matters

A small offline sparse-array operation has explicit coordinate and storage semantics.

1 / The failure

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

N = 1
observations = []
def solve(ptr):
    return sum(ptr[i+1]-ptr[i] for i in range(len(ptr)-1))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('interior empty',solve([0,1,1,3]),1)
check('all empty',solve([0,0,0,0]),3)
check('none empty',solve([0,1,2]),0)
check('singleton empty',solve([0,0]),1)
check('mixed',solve([0,2,2,2,5]),2)
check('no rows',solve([0]),0)
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
interior empty31Failed
all empty03Failed
none empty20Failed
singleton empty01Failed
mixed52Failed
no rows00Passed

SHA-256 / 8d429a6ed3b5c5fa7c01f9647eb2b59bbb3cd68630434f85093f30860c4f82dd

2 / The unsuccessful fix

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

N = 1
observations = []
def solve(ptr):
    return sum(ptr[i+1]-ptr[i]==1 for i in range(len(ptr)-1))
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('interior empty',solve([0,1,1,3]),1)
check('all empty',solve([0,0,0,0]),3)
check('none empty',solve([0,1,2]),0)
check('singleton empty',solve([0,0]),1)
check('mixed',solve([0,2,2,2,5]),2)
check('no rows',solve([0]),0)
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
interior empty11Passed
all empty03Failed
none empty20Failed
singleton empty01Failed
mixed02Failed
no rows00Passed

SHA-256 / 776a5d17f269064e6ac49a8000253ef45a5872f542bac488baf04864710eca4b

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

These are toy integer-valued COO or CSR contracts; they make no claim about a framework API, floating point policy, or large tensor performance. 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 2026-09-30T16:48:36.699476+00:00.

Case digest / 108643536221f2acc54bf64efb05f1181f19da66f62ad077b6da8109756cf20c