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Redundant knight
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Lyudmil Tsvetkov



Joined: 12 Jun 2012
Posts: 5988

PostPost subject: Re: Thanks    Posted: Sat Jun 21, 2014 6:53 am Reply to topic Reply with quote

bob wrote:
Lyudmil Tsvetkov wrote:
zullil wrote:
I really appreciate your many posts concerning evaluation. Although I haven't read each one---there are quite a few, after all Very Happy ---I've thought about many of them.

Now please don't take this the wrong way, but the main effect of your posts has been to convince me that this is not the way to go. Too many terms, too much hidden overlap (non-orthogonality), too many artifacts of the human approach to chess, motivated by our very limited search abilities.

At a fundamental level, it seems to me that evaluation comes down to mobility and attack. Even the material value of pieces is simply more or less an encapsulation of their mobilities. Admittedly this is overly simplistic (and focused on the opening and midgame), but a position is good for us if we can move to lots of squares and if we attack a lot of enemy material. After all, the goal of the game is to reduce the opponent's mobility to zero while simultaneously attacking his most valuable piece!

You've almost inspired me to revisit my primitive engine and, after improving the basic move generation and search, to focus on an evaluation based on mobility + attacking. Mostly as an academic exercise, since any engine I create would be just for fun (and also pretty weak).


Thanks Louis.

And I thought I posted just a few messages...

It depends on how you look upon it, I understand that very well. Different persons see different things. Nothing bad about that. But we are talking here how to perfect things. You are completely right, mobility is the most important thing (I would say immediately after space advantage Very Happy), but mobility comes in different ways: it comes with attacking, it comes with space, it comes with pawn features and it comes with imbalance evaluation. As mobility is reflected and substantiated in different ways, you can have a whole grasp of it only if you consider those different ways. And the more ways you consider, the closer you are to understanding mobility in-depth.

Now, I started hating that word - orthogonal. Lucas talks about orthogonality, Arjun talks about orthogonality, and now you also started doing this. You do not know what is orthogonal and what not until you test it. However, I completely agree that you do not need too many features in eval; but you need the most important ones. You can certainly get rid of unimportant terms.

I tell you again: the more terms you have in eval in a resonable way, the better, as they omit less possibilities of game development. This has been proven in engine history to be true, but people are always suspicious and unaccepting of new suggestions.

So you have an engine, hope to play a game against it one day. Very Happy

Your messages and especially output also always inspire me.


There is a key point you miss here. These programs literally search millions (or even tens of millions) of nodes per second. Basically an exhaustive search although to a variable depth. Every evaluation term you add has to be 100% correct, because otherwise your huge search space is guaranteed to walk over those positions where it doesn't work.

As you add more terms, there are more and more unexpected interactions that will cause things to add (or subtract) in a completely unexpected way and produce a score that makes you drop a pawn (or worse) in the blink of an eye.

Most of us that have done this for a while agree that one can't get very far on a minimalistic evaluation, but also one can't get very far with an overly complex evaluation either, because it is so difficult to debug an evaluation where some times the terms work in a coordinated way, while at other times they diametrically oppose each other and lead you to think things are equal when they are anything bug.

The search space has gotten so big, your "more terms is better" can quickly and easily backfire and generate something so complex it is difficult for a human to make heads or tails as to what is going on inside the tree.


That is the challenge: to be able to keep track of and update more terms.

That is why it is more difficult to write a top-notch engine nowadays than it used to be in the past.

And probably that is why many people like to çopy, or, what would you call it alternatively, make use of the already available knowledge. (legality and morality not discussed here)
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Subject Author Date/Time
Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 10:38 am
      Re: Redundant knight H.G.Muller Fri Jun 20, 2014 11:03 am
            Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 11:54 am
                  Re: Redundant knight H.G.Muller Fri Jun 20, 2014 4:01 pm
      Re: Redundant knight Lucas Braesch Fri Jun 20, 2014 11:21 am
            Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 12:03 pm
      Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 11:37 am
      Re: Redundant knight Louis Zulli Fri Jun 20, 2014 11:50 am
            Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 12:13 pm
                  Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 12:36 pm
                        Thanks Louis Zulli Fri Jun 20, 2014 1:27 pm
                              Re: Thanks Lyudmil Tsvetkov Fri Jun 20, 2014 2:09 pm
                                    Re: Thanks Arjun Temurnikar Fri Jun 20, 2014 2:32 pm
                                    Re: Thanks Louis Zulli Fri Jun 20, 2014 4:12 pm
                                    Re: Thanks Louis Zulli Fri Jun 20, 2014 4:21 pm
                                          Re: Thanks Lyudmil Tsvetkov Fri Jun 20, 2014 4:30 pm
                                    Re: Thanks Robert Hyatt Sat Jun 21, 2014 2:51 am
                                          Re: Thanks Lyudmil Tsvetkov Sat Jun 21, 2014 6:53 am
      Re: Redundant knight Arjun Temurnikar Fri Jun 20, 2014 1:41 pm
            Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 2:26 pm
                  Re: Redundant knight Arjun Temurnikar Fri Jun 20, 2014 3:03 pm
                        Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 3:40 pm
                              Re: Redundant knight Arjun Temurnikar Fri Jun 20, 2014 4:43 pm
            Re: Redundant knight Joerg Oster Fri Jun 20, 2014 2:33 pm
                  Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 3:12 pm
                        Re: Redundant knight Arjun Temurnikar Fri Jun 20, 2014 3:19 pm
                              Re: Redundant knight Arjun Temurnikar Fri Jun 20, 2014 3:35 pm
                                    Re: Redundant knight Lyudmil Tsvetkov Fri Jun 20, 2014 3:51 pm
                                    Re: Redundant knight Lucas Braesch Fri Jun 20, 2014 6:47 pm
                                          Re: Redundant knight Arjun Temurnikar Fri Jun 20, 2014 7:23 pm
                                                Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 1:31 am
                                                      Re: Redundant knight Bernhard Bauer Sat Jun 21, 2014 5:31 am
                                                            Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 6:57 am
                                                      Re: Redundant knight H.G.Muller Sat Jun 21, 2014 7:54 am
                                                            Re: Redundant knight Matthew R. Brades Sat Jun 21, 2014 8:04 am
                                                                  Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 8:57 am
                                                            Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 8:48 am
                                                                  Re: Redundant knight H.G.Muller Sat Jun 21, 2014 9:19 am
                                                                        Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 10:00 am
      Re: Redundant knight Bernhard Bauer Sat Jun 21, 2014 5:22 am
            Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 7:07 am
                  Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 9:30 am
                        Re: Redundant knight H.G.Muller Sat Jun 21, 2014 9:45 am
                              Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 10:21 am
                                    Re: Redundant knight H.G.Muller Sat Jun 21, 2014 11:31 am
                                          Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 11:38 am
                                          Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 11:38 am
                                                Re: Redundant knight H.G.Muller Sat Jun 21, 2014 11:52 am
                                                      Re: Redundant knight Arjun Temurnikar Sat Jun 21, 2014 2:23 pm
                              Re: Redundant knight Kevin Hearn Sat Jun 21, 2014 10:30 am
                                    Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 11:16 am
                                          Re: Redundant bishop Bernhard Bauer Sat Jun 21, 2014 11:36 am
                                                Re: Redundant bishop Lyudmil Tsvetkov Sat Jun 21, 2014 12:10 pm
                                                      Re: Redundant bishop H.G.Muller Sat Jun 21, 2014 12:16 pm
                                          Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 11:59 am
                                                Re: Redundant knight Lyudmil Tsvetkov Sat Jun 21, 2014 12:58 pm
                                          Re: Redundant knight H.G.Muller Sat Jun 21, 2014 12:11 pm
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