SgBWSet GoSafetyCommands::GetSafe(int& totalRegions, const string& type)
{
GoModBoard modBoard(m_bd);
GoBoard& bd = modBoard.Board();
GoRegionBoard regionAttachment(bd);
SgBWSet safe;
if (type == "benson")
{
GoBensonSolver solver(bd, ®ionAttachment);
solver.FindSafePoints(&safe);
}
else if (type == "static")
{
GoSafetySolver solver(bd, ®ionAttachment);
solver.FindSafePoints(&safe);
}
else
throw GtpFailure() << "invalid safety solver: " << type;
SgPointSet proved = safe.Both();
for (SgBWIterator it; it; ++it)
{
SgBlackWhite c = *it;
for (SgVectorIteratorOf<GoRegion> it(regionAttachment.AllRegions(c));
it; ++it)
if ((*it)->Points().SubsetOf(proved))
++totalRegions;
}
return safe;
}
/** List of safe points.
If no color is given, safe points of both colors are listed.
Arguments: benson|static [black|white]<br>
Returns: number of point followed bu list of points in one line.
*/
void GoSafetyCommands::CmdSafe(GtpCommand& cmd)
{
cmd.CheckNuArgLessEqual(2);
string type = cmd.Arg(0);
int totalRegions = 0;
SgBWSet safe = GetSafe(totalRegions, type);
SgPointSet set =
(cmd.NuArg() == 2 ? safe[BlackWhiteArg(cmd, 1)] : safe.Both());
cmd << set.Size();
for (SgSetIterator it(set); it; ++it)
cmd << ' ' << SgWritePoint(*it);
}
vector<SgPoint> GoUctDefaultMoveFilter::Get()
{
vector<SgPoint> rootFilter;
SgBlackWhite toPlay = m_bd.ToPlay();
SgBlackWhite opp = SgOppBW(toPlay);
// Safe territory
if (m_param.m_checkSafety)
{
GoModBoard modBoard(m_bd);
GoBoard& bd = modBoard.Board();
SgBWSet alternateSafe;
bool isAllAlternateSafe = false;
// Alternate safety is used to prune moves only in opponent territory
// and only if everything is alive under alternate play. This ensures that
// capturing moves that are not liberties of dead blocks and ko threats
// will not be pruned. This alternate safety pruning is not going to
// improve or worsen playing strength, but may cause earlier passes,
// which is nice in games against humans
GoSafetySolver safetySolver(bd);
safetySolver.FindSafePoints(&alternateSafe);
isAllAlternateSafe = (alternateSafe.Both() == bd.AllPoints());
// Benson solver guarantees that capturing moves of dead blocks are
// liberties of the dead blocks and that no move in Benson safe territory
// is a ko threat
GoBensonSolver bensonSolver(bd);
SgBWSet unconditionalSafe;
bensonSolver.FindSafePoints(&unconditionalSafe);
for (GoBoard::Iterator it(bd); it; ++it)
{
SgPoint p = *it;
if (m_bd.IsLegal(p))
{
bool isUnconditionalSafe = unconditionalSafe[toPlay].Contains(p);
bool isUnconditionalSafeOpp = unconditionalSafe[opp].Contains(p);
bool isAlternateSafeOpp = alternateSafe[opp].Contains(p);
bool hasOppNeighbors = bd.HasNeighbors(p, opp);
// Always generate capturing moves in own safe territory, even
// if current rules do no use CaptureDead(), because the UCT
// player always scores with Tromp-Taylor after two passes in the
// in-tree phase
if ( (isAllAlternateSafe && isAlternateSafeOpp)
|| isUnconditionalSafeOpp
|| (isUnconditionalSafe && ! hasOppNeighbors)
)
rootFilter.push_back(p);
}
}
}
// Loosing ladder defense moves
if (m_param.m_checkLadders)
{
for (GoBlockIterator it(m_bd); it; ++it)
{
SgPoint p = *it;
if (m_bd.GetStone(p) == toPlay && m_bd.InAtari(p))
{
if (m_ladder.Ladder(m_bd, p, toPlay, &m_ladderSequence,
false/*twoLibIsEscape*/) < 0)
{
if (m_ladderSequence.Length() >= m_param.m_minLadderLength)
rootFilter.push_back(m_bd.TheLiberty(p));
}
}
}
}
if (m_param.m_checkOffensiveLadders)
{
for (GoBlockIterator it(m_bd); it; ++it)
{
SgPoint p = *it;
if (m_bd.GetStone(p) == opp && m_bd.NumStones(p) >= 5 && m_bd.NumLiberties(p) == 2)
{
if (m_ladder.Ladder(m_bd, p, toPlay, &m_ladderSequence,
false/*twoLibIsEscape*/) > 0)
{
if (m_ladderSequence.Length() >= m_param.m_minLadderLength)
rootFilter.push_back(m_ladderSequence[0]);
}
}
}
}
if (m_param.m_filterFirstLine)
{
// Moves on edge of board, if no stone is near
const SgBoardConst& bc = m_bd.BoardConst();
for (SgLineIterator it(bc, 1); it; ++it)
{
const SgPoint p = *it;
if (m_bd.IsEmpty(p) && IsEmptyEdge(m_bd, p))
rootFilter.push_back(p);
}
}
return rootFilter;
}
