4 ms·
There are billions of valid games on a 2x2 board? Can anyone explain or link to something that explains how this is possible?
by sago 11y ago
There are billions of valid games on a 2x2 board? Can anyone explain or link to something that explains how this is possible?
- tromp 11y agoa single 2x2 game can visit as many as 48 of the 57 legal 2x2 positions, with many dozens of passes in between moves, and obviously many captures. This page http://tromp.github.io/java/go/twoxtwo.html http://tromp.github.io/java/go/twoxtwo.html on solving 2x2 go with various search methods may be helpful. I've lost track of my original 2x2 game counting code but suspect it was a close relative of this code.
- sago 11y agoWow, okay, thanks. I've a better respect for why Go is so hard to minimax now.
- Anderkent 11y agoIt's likely because a player might pass his move at any point; the game only ends when two players pass. So you don't need that many possible positions for a huge amount of possible games.
- fargo 11y ago. . . . | B . . . | B . W . | B B W . | . . W W | B . W W | B B . . | B B W . | B B . B | . . W . | . B W . | B B W . Loops are possible in a 2x2
- Anderkent 11y agoA move that returns to a previous board position is illegal, AFAIK. http://senseis.xmp.net/?TrompTaylorRules http://senseis.xmp.net/?TrompTaylorRules : 6. A turn is either a pass; or a move that doesn't repeat an earlier grid coloring
- tel 11y agoLoops are usually disallowed intentionally in this sort of thing, the so-called "superko" rule.
- drdeca 11y agoIsn't it generally a rule that the game board can never be returned to a state it was previously in?
- deleted 11y ago[deleted]
- tel 11y agoGenerally the rule is that you can't return the board to the position it was last in, but some rule sets extend it to any position it was ever in to avoid a few pathological scenarios. Without this infinite loops can exist.
- sago 11y agoIf it was because of loops, wouldn't there be infinite games?