> I don't see that, but then again I am not a very strong player > myself. What I notice is that it plays very "normal" until it's > pretty obvious that it's losing, not just when it varies slightly from > 50% but when it doesn't vary much from zero. However, it does play > more desperately once it varies significantly from 50% but certainly not > "meaninglessly." > > I don't like using the words "good" and "bad" when describing the > quality of the moves because I try to use terminology that's more > descriptive (although I fail miserably many times.) In a lost > position how do you distinguish one move from another when they all > lose? It sounds funny to me when you say (in so many words) that > once the program is losing it starts playing "bad moves."
At first move, the position is lost or won for one of the two players. Yet I am sure you could consider that some of the moves are good or bad. The only thing that matters is: Does this move increase my probability of winning against this opponent ? If two moves have the same result, which one is more beautiful ? I do not expect a computer to play Lasker way any time soon, so we might have to change the first criterion into ``against a generic opponent". Now when MC goes to the rampage, it's usually LESS efficient than if it was a little less desperate. The post of Baudis explains that well. I think the problem is that MC is overevaluating the probability that an opponent does not answer an easy threat, and, if playing against a human, lessen the probability of small imprecisions. When losing, look for an overplay. But a reasonable overplay... > Since this is a subjective quality can we use a subjective term such as > "normal" to describe moves that are cosmetically appealing to us? > And perhaps "ugly" to describe moves that are not? > > My feeling is that in lost positions, the only thing we are trying to > accomplish is to make the moves more cosmetically appealing (normal) and > at best improve the programs chances of winning against weak players. > After all, if the program is in bad shape, then to be completely > realistic it's probably going to lose to the player that put it in this > bad shape. Unless of course the program is being upset by a much > weaker player which can occasionally happen too. We can't reasonably > expect that if a program is quite sure that it is losing that the > program that it is beating it is not going to be aware of this too. > > It's also a bad mistake in my opinion to try to coerce it into playing > moves that are "normal" when an increasing amount of "desperation" is > indeed called for. I have presented anecdotes before about how chess > players have won games based on not playing as if things are normal when > they are losing, but instead suddenly playing differently which usually > consists of violating general principles and "normal" play. > > Again, I feel that this effect of moves that are not normal kick in > mostly when the position is very close to 0 or 1. So what we are > looking for is AT BEST a very minor improvement and we are wasting a lot > of energy on this. Agreed. > If the goal is to make the moves more cosmetically > appealing I can respect that more - that is realistic and probably even > easy to accomplish (and then the goal is to do it without weakening the > program too much.) Here I don't agree. Why should that weaken noticeably the program ? Same situation as before, it happens for won-lost positions: minor change in performance. > It's also being considered to use this to cover over some other weakness > such as nakade where the program doesn't understand the actual end of > the game and is thinking it has lost by 2 or 3 stones when in fact it > has a win. Aside from the fact that this is a fairly rare > occurrence, I believe it should be addressed directly, not with a > superficial treatment of the symptoms. > > So if you can make it win slightly more lost games by playing as if > nothing is wrong, then more power to you. It doesn't seem reasonable > to me that you should be able to do this by feeding the program false > information. You are effectively saying, "you are losing, be happy > with that." > > By the way, if this is to work (for instance for cosmetic reasons) I > don't think you can apply this gradually or based on previous > information. What if you are losing and the opponent plays a > blunder? After all, this is what has to happen since the program is > losing. You have to apply this based on information learned from the > current move you are searching. You can't gradually fold it in as the > game progresses and expect anything useful. I also agree about that. In fact, I think that in my previous suggestion to Hideki, winning rate after say 1000 simulations should be checked to be about that expected, and if not, komi should be adjusted again. > >> After all, the aim of tinkering with komi is to avoid that the computer > >> plays nonsensical moves, but it should know whether he must fight or > >> calm down. > >> > > > > Agree. So, it's important _when_ adjust komi or apply my method. My > > object is to keep winning rate around 50%, which yields good moves. > > > First of all, you won't keep the rate at 50% no matter what you do. At > some point the programs are able to completely resolve the position and > this happens surprisingly early in many cases with good programs. > If it's actually winning, then if you deduct a komi to convince it is > losing, you greatly increase the chances that it really will lose. If > you increase the komi to make it "try harder" to win a won game, it > won't start playing meaningful moves and you risk losing. > > You see, the problem is that once the score is significantly extreme in > either direction, there is no much you can do anyway, a single komi > point will change it suddenly to the OTHER extreme. But this is really > where most of the action is, so you have a catch-22. > > Go ahead, try this experiment: When the program is winning by over > 95%, see what happens when you tell it to "go for more" and see if > makes it win even more games. Agreed. That's why I think an evaluation function taking score into account is more reliable. As I said, with a very low importance of score, there's no reason to get weaker. Bouzy had indications that with a ``half-low'' (1/50 instead of 1/10000), you even could get some improvement. > I honestly believe you are barking up the wrong tree if you are looking > for program strength improvement. Probably true. I think the main motivation should be cosmetic. On the other hand, changing the evaluation function is probably very easy (a guess, since I do not program), so the pay is not that bad. Jonas _______________________________________________ computer-go mailing list computer-go@computer-go.org http://www.computer-go.org/mailman/listinfo/computer-go/
