inline void UniteWith(const Group &g, Position *next) {
		numLibs+=g.numLibs;
		libSum+=g.libSum;
		libSumSq+=g.libSumSq;

		next[last]=g.first;
		last=g.last;

		//for(std::set<Position>::iterator it=g.libs.begin(); it!=g.libs.end(); ++it)
		//	LibInsert(*it);
	}