Playing Strength, (Performance, Skill Level)
of a chess player, or chess playing entity, program or engine, reflects the ability to win against other players, given by a number or other element of an ordered set such as an ELO number.

The ability to solve test-positions, that is, finding the specified, likely one and only best move, might be an indicator for various particular engine skills, but does not necessarily correlate with playing strength. In his Parallelism and Selectivity in Game Tree Search lecture, Tord Romstad introduced the Worst Moves Observation (WMO), which states the practical playing strength is not primarily determined by the quality of the players best moves nor average moves, but by the quality of the players worst moves.

A statistical valid method to measure playing strength within a defined confidence interval is to play an appropriate huge number of games with both sides versus a wide range of different opponents ^{[2]} with symmetric time constraints, and to apply match statistics. Performance isn't measured absolutely; it is inferred from wins, losses, and draws against other players or engines. Players' rating depend on the ratings of their opponents, and the results scored against them ^{[3]}. While relative playing strength of chess engines is not strictly transmissive over various time controls, the number of games played is more relevant than their duration, the todays de facto standard in measuring playing strength is parallel playing fast chess with (ultra) short time control, such as blitz, bullet or even lightning chess, as for instance used in the Fishtest framework of Stockfish^{[4]}.

Home * Chess * Playing StrengthPlaying Strength, (Performance, Skill Level)of a chess player, or chess playing entity, program or engine, reflects the ability to win against other players, given by a number or other element of an ordered set such as an ELO number.

The ability to solve test-positions, that is, finding the specified, likely one and only best move, might be an indicator for various particular engine skills, but does not necessarily correlate with playing strength. In his

Parallelism and Selectivity in Game Tree Searchlecture, Tord Romstad introduced theWorst Moves Observation(WMO), which states the practical playing strength is not primarily determined by the quality of the players best moves nor average moves, but by the quality of the players worst moves.^{[1]}## Table of Contents

## Measuring

A statistical valid method to measure playing strength within a defined confidence interval is to play an appropriate huge number of games with both sides versus a wide range of different opponents^{[2]}with symmetric time constraints, and to apply match statistics. Performance isn't measured absolutely; it is inferred from wins, losses, and draws against other players or engines. Players' rating depend on the ratings of their opponents, and the results scored against them^{[3]}. While relative playing strength of chess engines is not strictly transmissive over various time controls, the number of games played is more relevant than their duration, the todays de facto standard in measuring playing strength is parallel playing fast chess with (ultra) short time control, such as blitz, bullet or even lightning chess, as for instance used in the Fishtest framework of Stockfish^{[4]}.## Strength

The strength of a chess program depends on many things, the quality and efficiency of the algorithms involved to determine the best move of a position, the balance of the so called search versus knowledge tradeoff to evaluate or compare leave nodes of a search tree, how to shape that tree and to propagate a score up to the root, and time management, that is how to allocate time for searching a move under time control requirements. Time used is roughly proportional to the number of visited nodes of the common depth-first search inside an iterative deepening frame, which grows exponentially by its effective branching factor raised to the power of search depth. Playing strength might be improved over the (playing) time due to learning algorithms.## See also

## Publications

## 1970 ...

1973).Mechanisms for Comparing Chess Programs.ACM Annual Conference, pdf1977).Chess Skill in Man and Machine. Springer, New York, N.Y. 2nd ed. 19831978).Performance Analysis of the Technology Chess Program. Ph.D. Thesis. Tech. Report CMU-CS-78-189, Carnegie Mellon University, CMU-CS-77 pdf » Tech1978).The Rating of Chessplayers, Past and Present. Arco Publications^{[5]}1979).Strength of a Chess Playing Computer. ICCA Newsletter, Vol. 2, No. 1## 1980 ...

1982).Computer Chess Strength. Advances in Computer Chess 31982).A Test for Comparison of Human and Computer Performance in Chess.Advances in Computer Chess 31982).The Bratko-Kopec experiment: a comparison of human and computer performance in chess. Advances in Computer Chess 31983).The Updated Bratko-Kopec Test.Computer Chess Digest Annual pp. 45-631984).Computer-Chess Tactics and Strategy. M.Sc. Thesis, University of British Columbia, pdf1984).The Truth about their Strength. ICCA Journal, Vol. 7, No. 41985).How to Bracket the Truth in Playing Strength. ICCA Journal, Vol. 8, No. 11985).A Hypothesis Concerning the Strength of Chess Programs. ICCA Journal, Vol. 8, No. 41989).Measuring the Performance Potential of Chess Programs, Advances in Computer Chess 51989).Playing Levels. Computer Chess News Sheet 23, pp 2, pdf hosted by Mike Watters## 1990 ...

1990).Speed, Processors and Ratings. Computer Chess News Sheet 25, pp 6, pdf hosted by Mike Watters1991).A taxonomy of concepts for evaluating chess strength: examples from two difficult categories. Advances in Computer Chess 6, pdf1992).Are You Sure It's Better?Selective Search 40, pp. 21, pdf hosted by Mike Watters1993).Rating Systems for Gameplayers, and Learning. ps1993).Rb+: the Dynamic Estimation of the Opponent's Strength. INESC-ID, Lisbon, Portugal » RB## 2000 ...

2002).Self-play: Statistical Significance. 7th Computer Olympiad Workshop2002).Reference Fallible Endgame Play. 7th Computer Olympiad Workshop, pdf2003).Self-Play: Statistical Significance. ICGA Journal, Vol. 26, No. 22007).Visualization and Adjustment of Evaluation Functions Based on Evaluation Values and Win Probability. AAAI 2007, pdf2008).Whole-History Rating: A Bayesian Rating System for Players of Time-Varying Strength. CG 20082009).Skill Rating by Bayesian Inference. CIDM 2009, pdf^{[6]}2009).Performance and Prediction: Bayesian Modelling of Fallible Choice in Chess. Advances in Computer Games 12, pdf## 2010 ...

2010).Predicting the Outcome of Chess Games based on Historical Data. IST - Technical University of Lisbon^{[7]}2011).Understanding Distributions of Chess Performances. Advances in Computer Games 13, pdf2011).A Discrete Evolutionary Model for Chess Players' Ratings. Physics and Society, arXiv:1103.1530v22012).Paired Comparisons with Ties: Modeling Game Outcomes in Chess. pdf preprint^{[8]}2012).Determining the Strength of Chess Players based on actual Play. ICGA Journal, Vol. 35, No. 12013).The Impact of the Search Depth on Chess Playing Strength. ICGA Journal, Vol. 36, No. 22015).Estimating Ratings of Computer Players by the Evaluation Scores and Principal Variations in Shogi. ACIT-CSI2015).Strength Improvement and Analysis for an MCTS-Based Chinese Dark Chess Program. Advances in Computer Games 14## Forum Posts

## 1990 ...

## 2000 ...

Re: A thought about ratings by Don Dailey, Computer Go Archive, December 10, 2007

Re: A thought about ratings by Edward de Grijs, Computer Go Archive, December 10, 2007

Re: A thought about ratings by Don Dailey, Computer Go Archive, December 10, 2007

## 2010 ...

2012## 2015 ...

2016^{[9]}About expected scores and draw ratios by Jesús Muñoz, CCC, September 17, 2016

2017## External Links

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## References

Dragon and Sundesigned by Carl Weinhold, art director of blacksmith and foundryFüssmann und Fleeth, Essen, exposed at the industrial and trade exhibition 1902 in Düsseldorf, and baught by Heinrich Flottmann as gate for his jackhammer factory, today adjacent to the exhibition and event space Flottmann-Hallen in Herne, North Rhine-Westphalia, Germany, and part of The Industrial Heritage Trail of the Ruhr area, "The dragon is a symbol of physical strength and intelligence with respect to the snake that symbolizes the tough, glowing wrought iron" from Flottmann-Tor – Hün un Perdün, see also Image by Gerd Biedermann, and Flottmann-Hallen - Historie (German)## What links here?

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