FA-84587 / Betting odds conversion / Member archive

Break-even book reported as an arbitrage · case 02

A book summing to exactly 100 percent is reported as a sure bet.

Member previewVariant 2 · 3 implementations · 8 checks per implementation

Case contract

Arbitrage finder. books rows are [bookmaker, outcome, decimal price]. For each outcome take the highest price; ties go to the alphabetically first bookmaker. S = sum of 1/best price. If S >= 1 return ["no arb"]. Otherwise stake_i = floor(total * (1/d_i) / S) cents; guaranteed return = min over outcomes of floor(stake_i * d_i). Return ["arb", [[outcome, bookmaker, stake] sorted by outcome], guaranteed return - sum of stakes].

Why this case matters

Odds comparison tools flag sure bets and split a bankroll across bookmakers.

One recorded failure

Sample boundary fixture

This sample comes from the broken implementation of a controlled reproducer.

Boundary fixture	Actual	Expected	Outcome
boundary exactly fair book	`["arb", [["away", "bravo", 5000], ["home", "alpha", 5000]], 0]`	`["no arb"]`	Failed

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