Author: Mogens Larsen
Date: 01:31:19 03/28/04
Go up one level in this thread
On March 28, 2004 at 02:21:21, Harald Lüßen wrote: >On March 27, 2004 at 20:34:15, Uri Blass wrote: >I use the described method of pondering in my engine Elephant and >I don't understand your problems. But my engine is weak, I have not >tested other methods, and you can convince me with good arguments. >Here is how I do it. > >After I have made my move and when I am waiting for a response I >switch colors and think for my opponent. Off course the search >starts automatically with the best move and pv line from the hash >table because I always get the pv from there and the move ordering >prefers hash moves. Very fast the iterative deepening comes to the >depth-1 of my last own search. Then the real work begins. The hash >table fills itself with more and deeper information, normally with >a deeper pv but in case of a sudden fail low or fail high at the >root there is a switch to the new pv. This is good because my >opponent will see it too and not follow the old line. In pondering >mode there is no timeout. Like in analyse mode this search goes >on forever. > >When I get an interrupt because of a winboard command (time or >usermove) I stop thinking, do the move, switch sides again and >start my own search. If my opponent played the predicted move >the hash tables are filled optimal but they have good informations >for other moves. That depends on the time my opponent has used >for his search. The longer the better and the more depth. Again >I reach the last depth-1 very quick and search my moves. When >I reach my time limit I stop my search and play the move. I don't >change my search time in pondering mode. Here is a place for >improvement. The time used for moves sometimes look like this: >me:10s opp:12s me:10s opp:5s me:10s opp:15s me:10s and so on. >I don't play immediately if my pondering predicted the right >move. > >I don't see why this is worse than not pondering or worse than >only pondering the predicted move. I agree. Without going into details about search vocabulary, the second approach has its virtues. In the case that the best candidate for opponent move is the best, you carry on as usual. If it's a really good move, hence really bad, you keep searching that move and maybe adjust the bounds for thinking time when it's your turn. But if you find a plausible refutation, you might as well search as if your predicted move was inferior and search for a better candidate to refute. That shouldn't be worse than no pondering if correctly implemented. Regards, Mogens
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