Othelloanian Capture

In Go and its variants groups are captured when they run out of liberties. Groups are defined as 'connected stones', which in square variants means 'orthogonally connected stones'. In the traditional method of capture, the captured stones are removed from the board, leaving behind empty territory.

In Othello and its variants 'lines' are captured using the custodian method, that is: the act of completing an enclosure of a straight unboken line of opponent's stones at both ends effectuates the capture. The captured line(s) are reversed to show the captor's color.

Othelloanian capture in Go variants unites both principles by enclosing groups and reversing them if captured. The most important consequence is that othelloanian capture does not lead to cycles, but at the price of not creating eyespace. It makes life harder to come by.

In Reversi Go the author illuminates the basic differences between traditional and othelloanian capture on a square grid, and considers the different consequences if suicidal moves are allowed or not, concluding in favor of the latter. One quote:

"Large and empty eye-spaces now also start to look very killable because capturing stones do not help form eyes (but rather take them away). Because of this, not getting surrounded would seem even more imperative than in normal Go. At the same time, actually capturing stones might be less attractive (unless as endgame play) because it does not form eyes, and thus capturing a stone solidly will not bring the strength to a weak group that it once did."

To generalize and extrapolate this: the method of capture appears to require an additional 'life insurance' to make it work properly. A legitimation is that the mechanism becomes 'cycle free' and thus avoids any of the related rule problems that are denied and discussed, at the same time, in Go circles. The means to get a sufficient degree of life insurance differ. Till now we have:

• The "Rosette", as applied in Medusa and Lotus. It looks and feels natural on a hexgrid but cannot simply be extended to the square grid. In terms of balance it fits the general strategy and tactics like a glove.
• The "Eye opener", as applied in Goncrete, invented by Luis Bolaños Mures. Basically it forces the captor to remove one stone of every group that is flipped in a capture, that is: if he can. And he can if and only if the removal does not split the group that resulted from the capture. Like the rosette, the rule is clearly a means to an end, but it is simple and effective and may soon feel 'natural' in actual play. In terms of balance it appears to fit the general strategy and tactics very well.

• "True liberties versus false liberties", a concept applied in Loose, invented by Luis Bolaños Mures. It solves the associated difficulties in the quest for life in a most elegant way: by turning 'false' liberties into 'true' eyes, in a capture. In the inventor's words:

"Reversi Go is already an interesting game, but not devoid of its own flaws, either, as making life is exceedingly hard. Concerned about this issue, I've designed Loose, a significant improvement on Reversi Go which solves this problem in a nice way while still being free of cycles. I've been trying to design the ideal finite Go variant for a long time, and Loose has the potential to be a good approximation to it."

• The "Safe Zone", as applied in Rin, invented by Zhen Wang, and Conversion Go, invented by Steven Meyers. Both games are closely related to Kropki, aka Dots, a fairly recent pencil & paper game with an obscure origin, probably in Eastern Europe or Russia. In Rin a group is immune from capture if it touches the edge of the board, Conversion Go narrows it down somewhat and requires a group to touch at least two different sides of the board to live unconditionally. Like the previous safety mechanisms, the conditions seem to fit the general mechanism of movement and capture fairly seamlessly.
• The "Symple move protocol", as featured in Symple and Sygo. This one doesn't 'wear its intent on its sleeve' for a simple reason: it wasn't intended as such. It is the move protocol required to create the quintessential implementation of Symple's thematic blend of territory and unification. Although Symple itself has no capture, the move protocol isn't game specific. Sygo is the result of its application to Go, and othelloanian capture was required because it serves the mechanism far better than traditional capture. That the mechanism, by allowing for multiple moves per turn, implicitly provides the 'life insurance' that the previous games had to add explicitly, is unintentional. A coincidence if you like. It's not to say that getting groups alive in Sygo is easy, but that the tactics required to do so are in alignment with strategy.

Christian Freeling

External links

Goncrete: http://www.lifein19x19.com/forum/viewtopic.php?f=45&t=4182

Rin: http://blog.zmxv.com/2010/12/rin-abstract-strategy-game.html

Conversion Go: http://home.fuse.net/swmeyers/conversion.htm

Kropki: http://www.dashstofsk.net/kropki.html

Dots: http://en.wikipedia.org/wiki/Dots_(game)

Symple: http://mindsports.nl/index.php/arena/symple

Sygo: http://mindsports.nl/index.php/arena/sygo