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93 votes
3 answers
6k views

A little number theoretic game

I came up with this little two player game: The players take turns naming a positive integer. When one player says the number $n$, the other player can only reply in two different ways: They can ...
Leif Sabellek's user avatar
19 votes
3 answers
1k views

The arithmetic progression game and its variations: can you find optimal play?

Consider the arithmetic progression game, a two-player game of perfect information, in which the players take turns playing natural numbers, or finite sets of natural numbers, all distinct, and the ...
Joel David Hamkins's user avatar
17 votes
3 answers
2k views

Traversing the infinite square grid

Starting somewhere on an infinite square grid, is it possible to visit every square exactly once, if at move $n$, one must jump $a_n$ steps in one of the directions north,south,east or west, and mark ...
mmm's user avatar
  • 171
13 votes
0 answers
221 views

A game based on the Euclidean algorithm

The following game is based on a somewhat "stupid" version of the Euclidean algorithm (where we allow only subtractions). Positions are given by finite non-empty multisets (repeated elements ...
Roland Bacher's user avatar
12 votes
1 answer
392 views

Euclid's algorithm as a combinatorial game

Consider the following two player game based on the Euclidean algorithm: Positions are given by $(a,b)$ in $\mathbb N^2\setminus\{(0,0)\}$ (where $\mathbb N=\{0,1,2,\ldots\}$) defining a greatest ...
Roland Bacher's user avatar
9 votes
1 answer
351 views

A Combinatorial Game with Integer Sequences

Two players, Alice and Bob, take turns constructing a sequence $a_1,a_2,a_3,\dots$, of distinct positive integers, none greater than a given parameter $K$. Alice plays first and makes $a_1=1$. ...
Bernardo Recamán Santos's user avatar
8 votes
1 answer
16k views

Analysis of Misere Nim?

My friend likes to impress people by playing 3-5-7 which has three piles of counters of sizes 3, 5 and 7. You can remove any number of coins from a single pile, the last player to move loses. ooo ...
john mangual's user avatar
  • 22.8k
6 votes
1 answer
196 views

A combinatorial game with seemingly curious arithmetic properties

We consider the following combinatorial game (with two players alternatively playing optimally). Posititions are given by heaps containing $b\geq 0$ black and $w\geq 0$ white stones and are encoded by ...
Roland Bacher's user avatar
4 votes
1 answer
432 views

"Infinity": A card game based on prime factorization and a question

I have been developing a card game called "Infinity", which involves a unique play mechanic based on card interactions. In this game, each card displays a set of symbols, and players match ...
mathoverflowUser's user avatar
3 votes
1 answer
462 views

Are Surreal Numbers the same as Trans-series?

I recently found the paper of Berarducci + Mantova [1, 2] saying that surreal numbers are equivalent to trans-series. These are very different objects: trans-series are used in physics to correct, ...
john mangual's user avatar
  • 22.8k
3 votes
0 answers
175 views

Does a generalized Queen split the upper P-positions of Wythoff Nim into two new beams of P-positions?

Wythoff Nim is an impartial game where 2 players take turns in reducing the heights of two finite heaps of tokens. Two types of moves are allowed (I) Remove any number of tokens from precisely one ...
Urban's user avatar
  • 71
2 votes
3 answers
462 views

A faster way to spoil an injection?

Ultimately this is about how primes jump. I will abstract the situation somewhat as there may be related applications which do not spring to my mind. I want to find small spoilers to Hall's Marriage ...
Gerhard Paseman's user avatar
1 vote
1 answer
147 views

Name for an easy combinatorial game

What is the name of the following combinatorial game: Two players, moving in turn. Positions: $0,1,2,\ldots$. Moves: $n\longmapsto n-1$ or $n\longmapsto \lfloor n/2\rfloor$ if $n>0$. No move for $0$...
Roland Bacher's user avatar
1 vote
0 answers
256 views

The maximum number of moves in a game of Nim [closed]

I was assigned a fun, but also quite hard problem for my computer science class - I have to write a java program that computes the maximum number of turns in an optimal game of Nim. In case you are ...
neobax's user avatar
  • 11