FA-12711 / Auction allocation rules / Open access

Pay-as-bid settlement treats every fill as one unit · case 01

Pay-as-bid settlement treats every fill as one unit.

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

ROOT CAUSE

Settlement omits filled quantities and charges each submitted order one unit price.

VERIFIED REPAIR

Implement the stated toy allocation contract directly: Given [bid-price, filled-units] rows of nonnegative integers, return each order charge price*filled-units; zero fill pays zero.

Unsuccessful approach: Suppressing the charge for zero fills still charges just one unit price for multiple filled units.

Case contract

Given [bid-price, filled-units] rows of nonnegative integers, return each order charge price*filled-units; zero fill pays zero.

Why this case matters

Deterministic teaching model for reviewing auction allocation software; not a representation of any venue or financial advice.

1 / The failure

Exit 1

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

N = 1
observations = []
def solve(rows):
    return [p for p,q in rows]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multi-unit fill', solve([[10+N,3],[5,0]]), [(10+N)*3,0])
check('single unit', solve([[9,1]]), [9])
check('zero price', solve([[0,5]]), [0])
check('no rows', solve([]), [])
check('several fills', solve([[3,2],[4,5]]), [6,20])
check('all unfilled', solve([[7,0],[8,0]]), [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 fixture	Actual	Expected	Outcome
multi-unit fill	`[11, 5]`	`[33, 0]`	Failed
single unit	`[9]`	`[9]`	Passed
zero price	`[0]`	`[0]`	Passed
no rows	`[]`	`[]`	Passed
several fills	`[3, 4]`	`[6, 20]`	Failed
all unfilled	`[7, 8]`	`[0, 0]`	Failed

SHA-256 / 0c745ca4d3ab667cc3efe68a6137019b384893e8ea10588e549ba9342f9aef0b

2 / The unsuccessful fix

Exit 1

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

N = 1
observations = []
def solve(rows):
    return [p if q else 0 for p,q in rows]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multi-unit fill', solve([[10+N,3],[5,0]]), [(10+N)*3,0])
check('single unit', solve([[9,1]]), [9])
check('zero price', solve([[0,5]]), [0])
check('no rows', solve([]), [])
check('several fills', solve([[3,2],[4,5]]), [6,20])
check('all unfilled', solve([[7,0],[8,0]]), [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 fixture	Actual	Expected	Outcome
multi-unit fill	`[11, 0]`	`[33, 0]`	Failed
single unit	`[9]`	`[9]`	Passed
zero price	`[0]`	`[0]`	Passed
no rows	`[]`	`[]`	Passed
several fills	`[3, 4]`	`[6, 20]`	Failed
all unfilled	`[0, 0]`	`[0, 0]`	Passed

SHA-256 / 6626cbae7cfa90d0550657f741a888dd5c4ac537502f739e449232bc229ff0db

3 / The verified repair

Exit 0

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

N = 1
observations = []
def solve(rows):
    return [p*q for p,q in rows]
def check(label, actual, expected):
    observations.append({"check": label, "actual": actual, "expected": expected, "passed": actual == expected})
check('multi-unit fill', solve([[10+N,3],[5,0]]), [(10+N)*3,0])
check('single unit', solve([[9,1]]), [9])
check('zero price', solve([[0,5]]), [0])
check('no rows', solve([]), [])
check('several fills', solve([[3,2],[4,5]]), [6,20])
check('all unfilled', solve([[7,0],[8,0]]), [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 fixture	Actual	Expected	Outcome
multi-unit fill	`[33, 0]`	`[33, 0]`	Passed
single unit	`[9]`	`[9]`	Passed
zero price	`[0]`	`[0]`	Passed
no rows	`[]`	`[]`	Passed
several fills	`[6, 20]`	`[6, 20]`	Passed
all unfilled	`[0, 0]`	`[0, 0]`	Passed

SHA-256 / f07e556309c2f9dd8deb512ea95a0b72d32ae62fef40cccd472c417492168aa4

Verification & scope

Offline toy model with explicit integer inputs; no strategic behavior or real market execution. 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 2026-09-29T14:38:59.432951+00:00.

Case digest / 378cb593bba1e5f3902e4e0a58127d3da009861aad6ebd38ebab78efb9bc164f