Search Heuristics and Heavy-Tailed Behaviour

Abstract. The heavy-tailed phenomenon that characterises the runtime distributions of backtrack search procedures has received considerable attention over the past few years. Some have conjectured that heavy-tailed behaviour is largely due to the characteristics of the algorithm used. Others have conjectured that problem structure is a significant contributor. In this paper we attempt to explore the former hypothesis, namely we study how variable and value ordering heuristics impact the heavy-tailedness of runtime distributions of backtrack search procedures. We demonstrate that heavy-tailed behaviour can be eliminated from particular classes of random problems by carefully selecting the search heuristics, even when using chronological backtrack search. We also show that combinations of good search heuristics can eliminate heavy tails from Quasigroups with Holes of order 10, and give some insights into why this is the case. These results motivate a more detailed analysis of the effect...

• Type: Conference
• Year: 2005
• Where: CP
• Authors: Tudor Hulubei, Barry O'Sullivan
• Keywords: Backtrack Search, CP 2005, Heavy-tailed Behaviour, Programming Languages, Runtime Distribution