<story><title>Ultimate Tic Tac Toe</title><url>http://mathwithbaddrawings.com/2013/06/16/ultimate-tic-tac-toe/</url></story><parent_chain><item><author>matchu</author><text>Here&amp;#x27;s an implementation that pretty much does exactly that. If someone can beat this bot, lemme know: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception-perfect&amp;#x2F;1681243068&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception-perfec...&lt;/a&gt;&lt;p&gt;And here&amp;#x27;s James Irwin&amp;#x27;s original implementation, auto-set to a Monte-Carlo AI and with a rules variation that (to my knowledge) prevents Perfect Bot from winning. Play with the config variables at the top for some other AIs and 2-player games and whatnot. &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception&amp;#x2F;1676336506&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception&amp;#x2F;167633...&lt;/a&gt;</text></item><item><author>quesera</author><text>I think the Orwin gambit can be extended to win the game every time.&lt;p&gt;- Force opponent to fill center miniboard, as he describes.&lt;p&gt;- Force opponent to fill (e.g.) northeast corner in the same way. Opponent now has taken two miniboards, and you have none, but you are one turn away from taking each of the remaining seven.&lt;p&gt;- Pick SW corner of SW corner. You have taken SW corner miniboard. Opponent is forced to play in same SW miniboard, already won by you.&lt;p&gt;- Pick SW corner of S. You have taken S miniboard. Opponent is forced to play in SW corner again, already won by you.&lt;p&gt;- Pick SW corner of SE corner. You have taken SE corner miniboard.&lt;p&gt;- Done. You win.&lt;p&gt;Like regular tictactoe, there is an advantage to going first. Unlike regular tictactoe, the advantage can&amp;#x27;t be compensated for. Otoh, the second player can use the same strategy with a little more carefulness, as long as they start early.&lt;p&gt;So either player can force the other into a protracted certain loss, unless there&amp;#x27;s an agreement or a rule against it. That&amp;#x27;s no fun.&lt;p&gt;EDIT: actually, you can win every time, in far fewer moves, and not using the Orwin gambit at all. It&amp;#x27;s not necessary to force your opponent to &lt;i&gt;fill&lt;/i&gt; any of the miniboards, not even the center.&lt;p&gt;I think this will win in ten moves and never lose driver control (excuse the notation): C&amp;#x2F;C, C&amp;#x2F;SW, C&amp;#x2F;S, [opponent takes C], C&amp;#x2F;SE, NE&amp;#x2F;SW, NE&amp;#x2F;S, NE&amp;#x2F;SE, [opponent takes NE], SW&amp;#x2F;SW [you take SW], SW&amp;#x2F;S [you take S], SW&amp;#x2F;SE [you take SE, and win]. A variation can be used by either player early in the game, but whoever starts with control would be foolish to lose it.&lt;p&gt;If this is a game played by mathematicians, either I&amp;#x27;m wrong, or there are additional rules. :)&lt;p&gt;EDIT2: C&amp;#x2F;C (first move above) is unnecessary. Nine moves. Perfect inning.</text></item></parent_chain><comment><author>NKCSS</author><text>Well, if the game would be changed to disallow &amp;#x27;moves&amp;#x27; in won sections, you&amp;#x27;d have a completely different game where this &amp;#x27;exploit&amp;#x27; of opponent trapping does not work.</text></comment>
<story><title>Ultimate Tic Tac Toe</title><url>http://mathwithbaddrawings.com/2013/06/16/ultimate-tic-tac-toe/</url></story><parent_chain><item><author>matchu</author><text>Here&amp;#x27;s an implementation that pretty much does exactly that. If someone can beat this bot, lemme know: &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception-perfect&amp;#x2F;1681243068&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception-perfec...&lt;/a&gt;&lt;p&gt;And here&amp;#x27;s James Irwin&amp;#x27;s original implementation, auto-set to a Monte-Carlo AI and with a rules variation that (to my knowledge) prevents Perfect Bot from winning. Play with the config variables at the top for some other AIs and 2-player games and whatnot. &lt;a href=&quot;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception&amp;#x2F;1676336506&quot; rel=&quot;nofollow&quot;&gt;https:&amp;#x2F;&amp;#x2F;www.khanacademy.org&amp;#x2F;cs&amp;#x2F;in-tic-tac-toe-ception&amp;#x2F;167633...&lt;/a&gt;</text></item><item><author>quesera</author><text>I think the Orwin gambit can be extended to win the game every time.&lt;p&gt;- Force opponent to fill center miniboard, as he describes.&lt;p&gt;- Force opponent to fill (e.g.) northeast corner in the same way. Opponent now has taken two miniboards, and you have none, but you are one turn away from taking each of the remaining seven.&lt;p&gt;- Pick SW corner of SW corner. You have taken SW corner miniboard. Opponent is forced to play in same SW miniboard, already won by you.&lt;p&gt;- Pick SW corner of S. You have taken S miniboard. Opponent is forced to play in SW corner again, already won by you.&lt;p&gt;- Pick SW corner of SE corner. You have taken SE corner miniboard.&lt;p&gt;- Done. You win.&lt;p&gt;Like regular tictactoe, there is an advantage to going first. Unlike regular tictactoe, the advantage can&amp;#x27;t be compensated for. Otoh, the second player can use the same strategy with a little more carefulness, as long as they start early.&lt;p&gt;So either player can force the other into a protracted certain loss, unless there&amp;#x27;s an agreement or a rule against it. That&amp;#x27;s no fun.&lt;p&gt;EDIT: actually, you can win every time, in far fewer moves, and not using the Orwin gambit at all. It&amp;#x27;s not necessary to force your opponent to &lt;i&gt;fill&lt;/i&gt; any of the miniboards, not even the center.&lt;p&gt;I think this will win in ten moves and never lose driver control (excuse the notation): C&amp;#x2F;C, C&amp;#x2F;SW, C&amp;#x2F;S, [opponent takes C], C&amp;#x2F;SE, NE&amp;#x2F;SW, NE&amp;#x2F;S, NE&amp;#x2F;SE, [opponent takes NE], SW&amp;#x2F;SW [you take SW], SW&amp;#x2F;S [you take S], SW&amp;#x2F;SE [you take SE, and win]. A variation can be used by either player early in the game, but whoever starts with control would be foolish to lose it.&lt;p&gt;If this is a game played by mathematicians, either I&amp;#x27;m wrong, or there are additional rules. :)&lt;p&gt;EDIT2: C&amp;#x2F;C (first move above) is unnecessary. Nine moves. Perfect inning.</text></item></parent_chain><comment><author>nkoren</author><text>The first one is beatable if -- and only if, I believe -- a square with two three-in-a-rows in it counts as both an X and an O. If this is the case, then O can win one round before X has a chance to it. But otherwise -- as you have it configured, where the first to get a three-in-a-row sets the larger square to either an X or an O -- it&amp;#x27;s unbeatable.</text></comment>