An O(n(2)L) time and O((n + k)L) space algorithm is provided for decid
ing whether or not a finite set C consisting of n words having total l
ength L, where all words are taken over a k-element alphabet, is a mul
tiset decipherable code. The algorithm is based on a technique related
to dominoes. At an early stage it decides in O(nL) time and O((n + k)
L) space whether or not set C is uniquely decipherable.