Detecting clones in game-playing software

The number of competitions using software agents in the AI or entertainment computing fields has grown over the years from a few to many. For instance, tournaments exist to let programs to play chess, checker, go, bridge, poker, simulated soccer, etc. While most competitions are organized for research purposes, some have a commercial side, thus raising the stakes for the software authors. Hence, plagiarism is becoming a problematic issue in the field of game-playing software agents used in competitions and tournaments. As new ideas and technologies are successfully implemented in open source programs, they will be reused and revisited by later programs until they become standard practices, but on the other hand the same phenomenon can lead to accusations and claims of plagiarism, especially in competitive scenarios, such as computer chess tournaments. Establishing whether a program is a "clone" or derivative of another can be a difficult and subjective task, left to the judgment of the individual expert and often resulting in a shade of gray rather than black and white verdicts. Tournaments judges and directors have to decide how similar is too similar on a case-by-case basis. This paper presents an objective framework under which similarities between game programs can be judged, using chess as a test cas