Summary
Proof-Number (PN) search is a best-first adversarial search algorithm especially suited for finding the game-theoretical value in game trees. The strategy of the algorithm may be described as developing the tree into the direction where the opposition characterised by value and branching factor is to expect to be the weakest. In this chapter we start by providing a short description of the original PN-search method, and two main successors of the original PN search, i.e., PN2 search and the depth-first variant Proof-number and Disproof-number Search (PDS). A comparison of the performance between PN, PN2, PDS, and αβ is given. It is shown that PN-search algorithms clearly outperform αβ in solving endgame positions in the game of Lines of Action (LOA). However, memory problems make the plain PN search a weaker solver for harder problems. PDS and PN2 are able to solve significantly more problems than PN and αβ. But PN2 is restricted by its working memory, and PDS is considerably slower than PN2. Next, we present a new proof-number search algorithm, called PDS-PN. It is a two-level search (like PN2), which performs at the first level a depth-first PDS, and at the second level a best-first PN search. Hence, PDS-PN selectively exploits the power of both PN2 and PDS. Experiments show that within an acceptable time frame PDS-PN is more effective for really hard endgame positions. Finally, we discuss the depth-first variant df-pn. As a follow up of the comparison of the four PN variants, we compare the algorithms PDS and df-pn. However, the hardware conditions of the comparison were different. Yet, experimental results provide promising prospects for df-pn. We conclude the article by seven observations, three conclusions, and four suggestions for future research.
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References
Allis, L.V.: Searching for Solutions in Games and Artificial Intelligence. PhD thesis, Rijksuniversiteit Limburg, Maastricht, The Netherlands (1994)
Allis, L.V., van der Meulen, M., van den Herik, H.J.: Proof-number search. Artificial Intelligence 66(1), 91–123 (1994)
Berkey, D.D.: Calculus. Saunders College Publishing, New York (1988)
Berliner, H.J.: The B*-tree search algorithm: A best-first proof procedure. Artificial Intelligence 12(1), 23–40 (1979)
Breuker, D.M.: Memory versus Search in Games. PhD thesis, Universiteit Maastricht, Maastricht, The Netherlands (1998)
Breuker, D.M., Allis, L.V., van den Herik, H.J.: How to mate: Applying proof-number search. In: van den Herik, H.J., Herschberg, I.S., Uiterwijk, J.W.H.M. (eds.) Advances in Computer Chess, University of Limburg, Maastricht, The Netherlands, vol. 7, pp. 251–272 (1994)
Breuker, D.M., Uiterwijk, J.W.H.M., van den Herik, H.J.: Replacement schemes and two-level tables. ICCA Journal 19(3), 175–180 (1996)
Breuker, D.M., Uiterwijk, J.W.H.M., van den Herik, H.J.: The PN2-search algorithm. In: van den Herik, H.J., Monien, B. (eds.) Advances in Computer Games, IKAT, Universiteit Maastricht, Maastricht, The Netherlands, vol. 9, pp. 115–132 (2001)
Breuker, D.M., van den Herik, H.J., Uiterwijk, J.W.H.M., Allis, L.V.: A solution to the GHI problem for best-first search. Theoretical Computer Science 252(1-2), 121–149 (2001)
Campbell, M.: The graph-history interaction: On ignoring position history. In: 1985 Association for Computing Machinery Annual Conference, pp. 278–280 (1985)
Campbell, M., Hoane Jr., A.J., Hsu, F.-h.: Deep Blue. Artificial Intelligence 134(1-2), 57–83 (2002)
Junghanns, A.: Are there practical alternatives to alpha-beta? ICCA Journal 21(1), 14–32 (1998)
Kishimoto, A.: Correct and Efficient Search Algorithms in the Presence of Repetitions. PhD thesis, University of Alberta, Edmonton, Canada (2005)
Kishimoto, A., Müller, M.: Df-pn in Go: An application to the one-eye problem. In: van den Herik, H.J., Iida, H., Heinz, E.A. (eds.) Advances in Computer Games 10: Many Games, Many Challenges, pp. 125–141. Kluwer Academic Publishers, Boston (2003)
Kishimoto, A., Müller, M.: A solution to the GHI problem for depth-first proof-number search. Information Sciences 175(4), 296–314 (2005)
Knuth, D.E., Moore, R.W.: An analysis of alpha-beta pruning. Artificial Intelligence 6(4), 293–326 (1975)
McAllester, D.A.: Conspiracy numbers for min-max search. Artificial Intelligence 35(1), 278–310 (1988)
Nagai, A.: A new AND/OR tree search algorithm using proof number and disproof number. In: Proceedings of Complex Games Lab Workshop, ETL, Tsukuba, Japan, pp. 40–45 (1998)
Nagai, A.: A new depth-first-search algorithm for AND/OR trees. Master’s thesis, The University of Tokyo, Tokyo, Japan (1999)
Nagai, A.: Df-pn Algorithm for Searching AND/OR Trees and its Applications. PhD thesis, The University of Tokyo, Tokyo, Japan (2002)
Nagai, A., Imai, H.: Application of df-pn+ to Othello endgames. In: Proceedings of Game Programming Workshop in Japan 1999, Hakone, Japan, pp. 16–23 (1999)
Nalimov, E.V., Haworth, G.M.C., Heinz, E.A.: Space-efficient indexing of chess endgame tables. ICGA Journal 23(3), 148–162 (2000)
Palay, A.J.: Searching with Probabilities. PhD thesis, Carnegie Mellon University, Pittsburgh, PA, USA (1983); Also published by Pitman, Boston (1985)
Pawlewicz, J., Lew, Ł.: Improving depth-first pn-search: 1 + ε trick. In: van den Herik, H.J., Ciancarini, P., Donkers, H.H.L.M(J.) (eds.) CG 2006. LNCS, vol. 4630, pp. 160–171. Springer, Heidelberg (2007)
Plaat, A., Schaeffer, J., Pijls, W., de Bruin, A.: Best-first fixed-depth minimax algorithms. Artificial Intelligence 87(2), 255–293 (1996)
Sackson, S.: A Gamut of Games. Random House, New York (1969)
Saito, J.-T., Chaslot, G., Uiterwijk, J.W.H.M., van den Herik, H.J.: Monte-carlo proof-number search for computer Go. In: van den Herik, H.J., Ciancarini, P., Donkers, H.H.L.M(J.) (eds.) CG 2006. LNCS, vol. 4630, pp. 50–61. Springer, Heidelberg (2007)
Sakuta, M.: Deterministic Solving of Problems with Uncertainty. PhD thesis, Shizuoka University, Hamamatsu, Japan (2001)
Sakuta, M., Iida, H.: The performance of PN*, PDS and PN search on 6×6 Othello and Tsume-Shogi. In: van den Herik, H.J., Monien, B. (eds.) Advances in Computer Games, Universiteit Maastricht, Maastricht, The Netherlands, vol. 9, pp. 203–222 (2001)
Schaeffer, J.: Conspiracy numbers. Artificial Intelligence 43(1), 67–84 (1990)
Schaeffer, J.: Game over: Black to play and draw in Checkers. ICGA Journal 30(4), 187–197 (2007)
Schaeffer, J., Burch, N., Björnsson, Y., Kishimoto, A., Müller, M., Lake, R., Lu, P., Sutphen, S.: Checkers is solved. Science 317(5844), 1518–1522 (2007)
Schaeffer, J., Lake, R.: Solving the game of Checkers. In: Nowakowski, R.J. (ed.) Games of No Chance, pp. 119–133. Cambridge University Press, Cambridge (1996)
Seo, M., Iida, H., Uiterwijk, J.W.H.M.: The PN*-search algorithm: Application to Tsume-Shogi. Artificial Intelligence 129(1-2), 253–277 (2001)
Winands, M.H.M., Uiterwijk, J.W.H.M., van den Herik, H.J.: PDS-PN: A new proof-number search algorithm: Application to Lines of Action. In: Schaeffer, J., Müller, M., Björnsson, Y. (eds.) CG 2002. LNCS, vol. 2883, pp. 170–185. Springer, Heidelberg (2003)
Winands, M.H.M., Uiterwijk, J.W.H.M., van den Herik, H.J.: An effective two-level proof-number search algorithm. Theoretical Computer Science 313(3), 511–525 (2004)
Winands, M.H.M., van den Herik, H.J., Uiterwijk, J.W.H.M.: An evaluation function for Lines of Action. In: van den Herik, H.J., Iida, H., Heinz, E.A. (eds.) Advances in Computer Games 10: Many Games, Many Challenges, pp. 249–260. Kluwer Academic Publishers, Boston (2003)
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van den Herik, H.J., Winands, M.H.M. (2008). Proof-Number Search and Its Variants. In: Tizhoosh, H.R., Ventresca, M. (eds) Oppositional Concepts in Computational Intelligence. Studies in Computational Intelligence, vol 155. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-540-70829-2_6
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