bob wrote: chrisw wrote: bob wrote: Rebel wrote: bob wrote: Rebel wrote: bob wrote:
chrisw wrote: Yes, I have indeed been on about "heavy eval" for years. Curious now how my "heavy eval" from early 1990s is the basis of Fruit. I think you use it too now.
On GM play, the sad truth is that you have no idea.
Fruit? Heavy Eval?
Chris did not say the Fruit eval is heavy.
How does that jive with the following quote?
Curious now how my "heavy eval" from early 1990s is the basis of Fruit. I think you use it too now.
By the mouth of Dann Corbit
a quote from Anthony Cozzie:
Anthony Cozzie quit chess programming because he felt that the winning program was nothing more than the biggest bag of tricks collected from all the existing programs.
How could you miss Chris' point?
How can one make a point with an outright false statement? There is nothing "heavy" (heavy is commonly a synonym for complex or computationally expensive in computer chess discussions) in Fruit's eval at all. Does he REALLY want to claim that a very simple bean-counter evaluation was derived from HIS evaluation?
One never knows what one is going to read here nowadays. But clearly, accuracy is not exactly a description of things like this.
Fruit's eval is NOT "heavy" by any possible measure of the term. Here's the typical "slang" definition of heavy (not particularly computer-science specific, but the last one is on point...
Usher is a heavy dancer.
* Cool, Awesome
Wow your website is heavy.
* deep, hard to deal with, burdensome, or hard to understand
BTW where does CSTal come in here? It was never open-source, and I have never heard of anyone reverse-engineering the thing since it was never near the top of any rating list or tournament. How, then, did someone (Fabien) supposedly hijack his eval ideas? So other than being totally unrelated to current state of affairs, how exactly was there a point to be made???
Who said anything about Fabien hijacking? Oh, you made it up. Why that?
CSTal doesn't need to be reverse engineered since the ply one static scores are all displayed and the evaluation function idea can be worked out from that, in particular the king attack function idea. Also I made quite enough noise so those other than your blindedness can quite easily work out what it was doing.
For strong chess players with GM level knowledge, of course heavily used by Tal, it's Q plus 2 units is quite possibly a mate, and if not likely there's a perpetual. One of the units can be a pawn, the more and the stronger units, the greater the mate chances. Defenders are irrelevent. Defending king pawn structure damage is very relevent. R+R can substitute for Q.
For slower ones, software engineers who need source code ....
if queen plus unit
get attacks around the king using suitable mask
use the total attacker type melded with pawn destruction to give a suitable bonus.
for CSTal this was along the lines of
Q plus unit plus pawn worth two pawns or so
Q plus two units worth a bishop
Q plus three units worth a rook, all adjusted for pawn defense destruction.
Apart from the bonus size, looks quite like Fruit Rybka and Crafty some time after Fruit, doesn't it?
Not in Fruit or RYbka as far as I know were side next to move bonuses, if safe checks, especially Q checks available, increase bonus quite a lot. If not on move decrease bonus. Twas much more making it probbaly too heavy but I forget nearly two decades later.
This stuff was in first half of 1990s, I suspect quite unique to CSTal. Also other stuff relating to material imbalances. Why does it look similar in fruit? No idea, probably people with minds open more than Hyatt discussed the ideas and worked them out, they are pretty obvious to a strong chess player programmer, again not Blinded ones with preconceived ideas.
One thing is absolutely for sure, the first programmer who got this new idea with relatively low computation costs into a fast searcher was going to wipe the board with the opposition. But Hyatt never realised that, until he copied the concept from Rybka/Fruit.
I didn't copy any king safety stuff from Fruit/Rybka. Not one thing. That seems to be the difference between "us". Some of us can actually design and write code without copying the work of others. Some take the easy way out. Feel free to show me ANY king-safety concept in Crafty that is related to Fruit. Anything at all will do just fine for discussion.
What you describe doesn't look like what Crafty does at all, sorry. If you had looked a bit you would already know that.
Crafty computes two distinct values. King shelter (pawns, holes in them, open files, weak squares, and such, all related to the king's position) and king tropism (how close a piece is to the king (or how close it attacks squares to the king in the case of sliders). These two values are used as indices into an array that makes it more important to attack an exposed king (shelter) and less important to attack a safe king position.
What does that have to do with what you were doing? I've been doing scoring like this forever. The 2d array values have been heavily tuned by cluster testing, but the concept is about as simple as it gets.
Just to be absolutely clear I said you "copied the concept". Nothing about code.
And, the concept in Crafty 2005 did not appear in Crafty 1990's.
Conceptually, CSTAl did the following for king attack inter alia of course .....
A. CSTal, Forget the whole thing if inadequate material to build a King attack.
Crafty, also checks for adequate material and reduces bonuses if found. Concept similar, scale not.
B. CStal, build attacker mask and hence king attackers based on a pattern around the king.
Crafty, build king attackers based on proximity to king. Same concept, implementation different.
C. CSTal, fold in pawn structure destruction. Get exponentially increasing score (based on attack size and pawns)
Crafty, here from my memory, but basically: score the king attack material from an exponential table. Score the pawn destruction and modify the previous score.
Same concept, but implemenation different.
I think the key to the idea is the exponential ramping of the score based on attack strength. CStal, Fruit, Rybka, Crafty. And the use of attacker quantity and pawn destruction. Chessically the concepts are parallel.
Now, Bob, nobody knows where you got these ideas or concepts from, or whether you dreamed them up independently. But timeline facts are CSTal, 1990s. Others 2000s. As I said before, I am not complaining, nor do I think anythign "bad" has happended, just pointing out that there seems to be a developmental pattern here, one person has a new idea, and within some time, everybody, or most are usign the idea, possibly much modified, but the idea nevertheless.