Optimal detection of a counterfeit coin with multi-arms balances Original Research Article

We consider the problem of locating a light coin out of a set containing n coins, n − 1 of which have the same weight. The weighing device is a balance with r ⩾ 2 pans that, when r equally sized subset of coins are weighted, indicates the subset eventually containing the light coin. We give an algorithm to find the counterfeit coin that requires the minimum possible average number of weighings. All previous results on this problem considered two-arms balances only.