On Nov 13, 2007 3:57 PM, Petr Baudis <[EMAIL PROTECTED]> wrote: > On Tue, Nov 13, 2007 at 03:32:03PM -0500, John Tromp wrote: > > On Nov 13, 2007 2:48 PM, Petr Baudis <[EMAIL PROTECTED]> wrote: > > > > > I'm now somewhat torn. The speedup from using pseudo-liberty counts > > > could be huge, estimating from my profiling. On the other hand, it > would > > > be very useful to still be able to quickly check if a group is in > atari > > > - it looks like if atari stones would get special attention during the > > > random games, that could make the bot a lot stronger. > > > > > > Is there any known way to get the best of the both worlds? :-) > > > > Yes, you can generalize pseudoliberties by extending them > > with another field, such that if the (summed) pseudoliberty field > > is between 1 and 4, then the other (summed) field will tell you if all > these > > are coming from a single true liberty. > > Wow, that's great idea! I was trying to think along these lines but > realized the implementation only after reading what you wrote. > > I guess you mean something in the spirit of: > > group.xyzzy = 0 > > add_liberty(group, coord) > group.xyzzy += as_int(coord) > > remove_liberty(group, coord) > group.xyzzy -= as_int(coord) > > in_atari(group) > group.pseudlibs <= 4 && is_liberty(group, as_coord( > group.xyzzy))
You're right, that would work. PS: I think that last one should be: group.pseudlibs <= 4 && is_liberty(group, as_coord(group.xyzzy /group.pseudlibs))
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