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## Which popular games are the most mathematical?

I consider a game to be mathematical if there is interesting mathematics (to a mathematician) involved in

• the game's structure,
• optimal strategies,
• practical strategies,
• analysis of the game results/performance.

Which popular games are particularly mathematical by this definition?

Motivation: I got into backgammon a bit over 10 years ago after overhearing Rob Kirby say to another mathematician at MSRI that he thought backgammon was a game worth studying. Since then, I have written over 100 articles on the mathematics of backgammon as a columnist for a backgammon magazine. My target audience is backgammon players, not mathematicians, so much of the material I cover is not mathematically interesting to a mathematician. However, I have been able to include topics such as martingale decomposition, deconvolution, divergent series, first passage times, stable distributions, stochastic differential equations, the reflection principle in combinatorics, asymptotic behavior of recurrences, $\chi^2$ statistical analysis, variance reduction in Monte Carlo simulations, etc. I have also made a few videos for a poker instruction site, and I am collaborating on a book on practical applications of mathematics to poker aimed at poker players. I would like to know which other games can be used similarly as a way to popularize mathematics, and which games I am likely to appreciate more as a mathematician than the general population will.

Other examples:

• go
• bridge
• Set.

Non-example: I do not believe chess is mathematical, despite the popular conception that chess and mathematics are related. Game theory says almost nothing about chess. The rules seem mathematically arbitrary. Most of the analysis in chess is mathematically meaningless, since positions are won, drawn, or tied (some minor complications can occur with the 50 move rule), and yet chess players distinguish strong moves from even stronger moves, and usually can't determine the true value of a position.

To me, the most mathematical aspect of chess is that the linear evaluation of piece strength is highly correlated which side can win in the end game. Second, there is a logarithmic rating system in which all chess players say they are underrated by 150 points. (Not all games have good rating systems.) However, these are not enough for me to consider chess to be mathematical. I can't imagine writing many columns on the mathematics of chess aimed at chess players.

Non-example: I would exclude Nim. Nim has a highly mathematical structure and optimal strategy, but I do not consider it a popular game since I don't know people who actually play Nim for fun.

To clarify, I want the games as played to be mathematical. It does not count if there are mathematical puzzles you can describe on the same board. Does being a mathematician help you to learn the game faster, to play the game better, or to analyze the game more accurately? (As opposed to a smart philosopher or engineer...) If mathematics helps significantly in a game people actually play, particularly if interesting mathematics is involved in a surprising way, then it qualifies to be in this collection.

If my criteria seem horribly arbitrary as some have commented, so be it, but this seems in line with questions like Real world applications of math, by arxive subject area? or Cocktail party math. I'm asking for applications of real mathematics to games people actually play. If someone is unconvinced that mathematics says anything they care about, and you find out he plays go, then you can describe something he might appreciate if you understand combinatorial game theory and how this arises naturally in go endgames.

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Yeah, well the rules of mathematics are chessly arbitrary. – Harry Gindi Feb 1 2010 at 11:19
I think it's a mischaracterization to say chess is nonmathematical; it's just that chess, like so many things one encounters in the real world, is neither elegant nor simple from the point of view of mathematics. That game theory can't tell us much about chess tells us more about the limitations of game theory than about the mathematical nature of chess. That said, your suggested examples are definitely better. – Mark Meckes Feb 1 2010 at 14:29
This is very far from 'give a list of all games.' One hope is to find other popular games whose play involves mathematics. Another is to learn more real mathematics about games I already know. A third idea is to see what resonates with other mathematicians. I'm sorry if you don't find these interesting, or if you find my criteria arbitrary--I don't see a huge difference between this and questions like, "What are neat applications of mathematics/this field?" – Douglas Zare Feb 1 2010 at 17:56
You disagree with my statement that Nim is not actually played for fun? I can show you go clubs, bridge clubs, backgammon clubs, even a "world championship of rock-paper-scissors," etc. I've never seen a Nim club or heard someone describe himself or herself as a Nim player. There are many theoretical games people don't actually play, and I don't think it's arbitrary to exclude those. I'll clarify my reasons for excluding chess later. – Douglas Zare Feb 1 2010 at 23:17
In "l'année dernière à Marienbad" ("last year in Marienbad"), a movie by Alain Resnais, you can see people playing Nim for fun. Now this just moves the problem, because I don't know anyone watching that movie for fun. (I just mean that peculiar movie. Resnais made a lot of very good movies. But that one is a serious contender for the prize of the most boring movie ever). – Joël Oct 7 2011 at 19:31

There is a popular game in current cellphones called Pixelated (in BlackBerry) or Flood-It (in iPhone) that has a very interesting analysis (its generalization is equivalent to the Shortest superstring problem): http://arxiv.org/abs/1001.4420 http://www.cs.bris.ac.uk/Research/Algorithms/BAD10/Slides/Jalsenius.pdf

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There's also Nine Men's Morris, which is a very ancient game. My understanding is that it has been effectively solved in recent years with the help of computer analysis.

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The Legend of Zelda and several other classic Nintendo games are NP-hard. http://arxiv.org/pdf/1203.1895v1.pdf

Following the example of Rubik's Cube (i.e. maybe not exactly a game), as a kid I was fascinated by Spirograph and played it for hours on end.

There is always "Who can name the bigger number" (you can win the computable version (second link below) with large cardinals):

Pool (aka billiards) has always seemed mathematical to me. A buddy of mine told me he learned about PDE's from trying to calculate the motion of a ping pong ball (laminar airflow etc).

Enough, I'll stop.

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Diplomacy was pretty much invented to illustrate points in cooperative game theory. At least, that's how Martin Shubik told me the story. :)

Actually, I think he invented a card game called "So long, Sucker", and claimed Diplomacy was based on that.

That said, the core points are psychological -- if somebody knows he is losing but has the power to choose the winner, on what basis does he choose?

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I would be tempted to include Blackjack in the list of mathematical games. It's supposedly a game of chance, but gambling establishments routinely forbid card counting, because a mathematical approach to the game gives the player too big of an advantage. This rule is typically enforced through a mathematical analysis of the player's bets.

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Khet is a great new game awarded by Mensa. There is even a master thesis dedicated to it: http://www.personeel.unimaas.nl/Uiterwijk/Theses/MSc/Nijssen_thesis.pdf

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Rummikub ? It encourages some logical thought and analysis. It seems to have at least one mathematical paper on it

http://comjnl.oxfordjournals.org/content/49/6/665.abstract

and it's popular and fun.

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The page http://www.toothycat.net/~hologram/Turing/index.html claims that the popular trading card game Magic: The Gathering is Turing complete. Some mathematician who knows the rules should recheck the proof.

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Heads or Tails - Is it popular game? There is a lot of mathematics related with this game. For example, it's non-transitive variant - Penney's game.

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Untangle (available in Debian based distros and easy online HTML5 version

From the documentation:

You are given a number of points, some of which have lines drawn between them. You can move the points about arbitrarily; your aim is to position the points so that no line crosses another.

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There is the amazing set of one-player games presented by S. Tatham (especially loopy and towers):

http://www.chiark.greenend.org.uk/~sgtatham/puzzles/

You should try it !

Damien.

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I’d like to emphasize that typical sports games (eg. played at Olympic games, NFL, MLB, NBA, NHL) often fit at least three criteria mentioned in the question. Before me, Barry Cipra mentioned baseball. These games are very useful to ‘popularize mathematics’, more precisely applied mathematics (operations research). Being a mathematician can help you play the game better (sometimes as a coach because we think of optimal strategies). And ‘mathematics is involved in a surprising way’ as people (students) generally don’t expect mathematics can help in such situations. The techniques used involve eg. dynamic programming, probability trees, game theory and Monte Carlo methods. As examples, I could give the following papers: a) Beaudoin, D., & Swartz, T. B. (2010). Strategies for pulling the goalie in hockey. The American Statistician, 64(3), 197-204; b) Clarke, S. R., & Norman, J. M. (2012). Optimal challenges in tennis. Journal of the Operational Research Society, 63(12), 1765-1772 c) Annis, D. H. (2006). Optimal end-game strategy in basketball. J Quant Anal Sports, 2(2). d) Kostuk, K. J., & Willoughby, K. A. (2006). Curling's paradox. Computers & operations research, 33(7), 2023-2031. e) Chiappori, P. A., Levitt, S., & Groseclose, T. (2002). Testing mixed-strategy equilibria when players are heterogeneous: the case of penalty kicks in soccer. American Economic Review, 1138-1151. f) Tibshirani, R. J., Price, A., & Taylor, J. (2011). A statistician plays darts. Journal of the Royal Statistical Society: Series A (Statistics in Society), 174(1), 213-226.

For more on the topic, I recommend (Wright MB. “50 years of OR in Sport”. Journal of the Operational Research Society (2009) 60:S161-S168) or the short intro to this paper to be found here: http://ifors.org/web/ifors-september-2009-newsletter/. Moreover, Journal of Quantitative Analysis in Sports can also be of interest.

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The two-player single suit whist has been analyzed completely in this paper by Johan Wastlund. This was mentionned by Alison Miller in her answer to my MO question Bridge game with only one suit: strategy.

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Being a mathematician allows you to play the game of chess better.

Mathematicians perform calculations quickly and accurately. Mathematicians are creative. Mathematicians are good at identifying the important component to a problem. Mathematicians are accustomed to encountering new problems and challenges. Mathematicians are good at comparing alternatives.

Now consider the game of chess. At any level 90%+ of chess games end as a result of an oversight in calculation. This often happens because one misses a surprising or unconventional move that requires creativity. In chess there are many strategic components, pawn structure, piece activity, material imbalance, king safety etc. but often one of these takes center stage. Almost always in a game of chess there will be a situation you have never encountered before. 90+% of grandmaster chess moves would be listed in the top 5 choices of any tournament player but consistently play the third or fourth choice move is a recipe for disaster even in scholastic chess.

I can not think of a profession better suited to playing chess than that of mathematician!

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The best mathematician chess players in history are: Emmanuel Lasker John Nunn (who appears to have published in "Topology" as J. D. M. Nunn). There are some people who were strong masters once upon a time (Sarnak,Formanek) I don't agree with Doug's claim that time pressure is the culprit (many good mathematicians were good at mathematics contests), but the real point (imho) is that the amount of self-discipline and effort needed to become a strong tournament chess player is much greater than the intrinsic interest of the game (if you want to work that hard, why not work on mathematics? – Igor Rivin Jan 16 2011 at 21:58
Well, in my college chess teams, most of the chess players were studying mathematics or computer science; but it was very noticeable that the best mathematicians were only average chess players, and vice versa, with few exceptions. (And, several of the top mathematicians didn't play at all). Former World Chess Champion Karpov gave up mathematics at university because mathematics and chess were "incompatible". These are not statistically significant samples, of course! – Zen Harper Jun 8 2011 at 1:24
Former world champion Dr. Botvinnik was also an electrical engineer. – Zen Harper Jun 8 2011 at 1:28

There are various map/graph colouring games which are more subtle than determining the chromatic number. For example take a planar graph or map (particular or restricted to some category) - how many colours can P1 force P2 to use: or who wins if the first person forced to use a fifth colour loses?

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Just a two cents worth here. :) Chess itself might perhaps not be too mathematical, but the chess evaluation functions of any chess-playing computer program seems like a mathematical object. After all, these are maps from the set of chess positions to $\mathbb{R}$ and they are bound to satisfy various properties. Given any two chess programs that are both strong and might be expected to be decent (in terms of current technology) approximations to objective truth, one might probably expect them to be "close" in some meaningful way that one could perhaps attempt to define.

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Blood Bowl! All about managing probability. http://en.wikipedia.org/wiki/Blood_bowl

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I am a bit surprised that Dominion has not been mentioned yet. I am referring less to the gameplay itself rather than to the analyzes that people do in order to assess the "intrinsic worth" or "situational worth" (my terms) of a card or a strategy, using a rather complicated simulator. I perceive it as a kind of Monter Carlo analysis.

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Games are mathematical. That's not something you can avoid. If there are rules for moves and goal states, you've already entered mathematics through logic and proof theory. And even for the simplest games, there is a rich mathematical theory studying it's structure and analysing results.

Mathematicians aren't just interested in finding optimal strategy and assigning a solution to a game. They also look to generalise and abstract theories of the gameplay and find ways to evaluate statements in the ontology of the game. Even simple games have rich logical calculi, and there are questions of rule independence and game extensions that can always be asked.

Dynamic Epistemic Logic is one of the general settings in which more advanced theories of game play have been formulated. Whenever two or more people are involved in gameplay, there are important distinctions between belief, knowledge, shared knowledge, and strategy that must be made to fully understand the dynamics. DEL (and a number of related settings) have been used to evaluate many common games, from simple pebble and card games to complicated board games and beyond, as a means to understand the evolution of belief systems and evaluate strategy during the play.

The Dynamic Epistemic Logic of Games

Epistemic Logic and the Foundations of Decision and Game Theory

Selection Monads and the Relation Between Game Theory and Proof Theory

I think the real mathematical answer to your question, then, is every popular game. There's no "most mathematical". Proof theory, models, modal logics, agent calculi and bisimulation lie at the heart of all games.

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How would you start an analysis of the party game Charades? Gerhard "Or Worse Yet, Of Pictionary" Paseman, 2013.01.30 – Gerhard Paseman Jan 31 at 1:57