[rules-users] Why is solving a partial puzzle much slower than generating one from scratch?

I am making a 3x3 Sudoku solver with Drools planner. The planning entities are the digits. The problem facts are the rows (planning variable) and columns. When I set Drools Planner to solve a problem where no digit is initialized, it gives a perfect solution in ~15 secs. But when I set a few digits as initialized, it never finds a solution. It always lists 8 hard constraints broken on termination. I implemented the moves as: if(digit.getFixed()==false){ moveList.add(new RowChangeMove(digit, toRow)); } If the digit is fixed, dont make a move object for it. Earlier, I implemented it in isMoveDoable: if the digit.getFixed() is true, it returns false. Both do not work. 20:31:13.442 [main] INFO o.d.p.c.l.DefaultLocalSearchSolverPhase - Phase local search finished: step total (978), time spend (60061), best score (-8). 20:31:13.442 [main] INFO o.d.p.core.solver.DefaultSolver - Solved: time spend (60061), best score (-8), average calculate count per second (7433). -- View this message in context: http://drools.46999.n3.nabble.com/Why-is-solving-a-partial-puzzle-much-sl... Sent from the Drools: User forum mailing list archive at Nabble.com.