Message #2259

From: castavernas2002 <castavernas2002@yahoo.com>
Subject: Spinpossible – Simple but extremely challenging group theory based puzzle
Date: Fri, 08 Jun 2012 13:41:52 -0000

Hey guys, I’m new here and Melinda suggested I check out the group and post about Spinpossible and some of the open math surrounding it.

Spinpossible is a (free) puzzle game that you can play here: https://spinpossible.com/index.pl or on your iphone or android phone.

The idea is very simple. There are 9 tiles, ordered 1-9 and laid out in a grid. You can manipulate them by rotating any rectangular group of them 180 degrees. The goal is to get all tiles right-side up, in order, 1 through 9.

Despite the simplicity, the game is extremely challenging and there are a lot of deep group theory questions related to the game, for more details see this paper on archiv, http://arxiv.org/abs/1110.6645. Some of the simpler interesting results are that,

(a) every puzzle can be solved in at most 9 spins.
(b) every puzzle can be solved in at most 9 spins even if you are not allowed to spin individual tiles

However, all these results have been shown only by brute force, computationally and the 4x4 version of the game, with 16 tiles, is believed to be computationally intractable.

Researchers both in CS and in Mathematics worldwide have gotten interested in the game and we had a very successful presentation at the JMM 2012 in Boston where a math professor recommended I get in touch with Melinda Green and post to this group, so I hope you enjoy it.

We’re still tweaking the puzzle so any helpful suggestions/comments are greatly appreciated.

Thanks!

Alex Sutherland