Moderators: hgm, chrisw, Rebel
I haven't checked the source if Pedantic implements extra pruning. However you can check if plain negamax(full search without pruning) finds the mate . This quick check might save lot of hours IMO.
[fen]r2n2k1/3P3p/1R4p1/2B5/4p3/2P1P2P/p4rP1/2KR4 w - - 0 40[/fen]JoAnnP38 wrote: ↑Tue Jan 10, 2023 7:39 pm Okay, I found an engine supposedly rated 2050 ELO and I actually won a game for the first time. However, in the rematch I am scratching my head. Why doesn't Pedantic see the move a2a1Q at 40 that leads to mate? I've debugged it a little and see that the increase in material is being updated. The PV pedantic suggests doesn't even push it into the horizon. Sigh... more work, more work.
I think you guys were both right. I only solved the problem by going back to basics and creating the simplest Negamax search I could -- no quiesence, no transposition tables, no pruning and no null window searches. An as @okidoki points out I discovered my problems. Biggest one had to do with the transposition table. I had some logic reversed which of course broke the search. As I slowly added features back into the search I found other bugs, so it was a very fruitful endeavor. I wish I had started like that. I depended on my unit tests, but if you are developing code around ideas that you don't fully grok... Well, the tests are only as good as my knowledge.
Code: Select all
>Pedantic /?
Description:
The pedantic chess engine.
Usage:
Pedantic [command] [options]
Options:
--version Show version information
-?, -h, --help Show help and usage information
Commands:
uci Start the pedantic application in UCI mode.
perft Run a standard Perft test.
>Pedantic perft /?
Description:
Run a standard Perft test.
Usage:
Pedantic perft [options]
Options:
--type <Average|Details|Normal> Specifies the perft variant to execute. [default: Normal]
--depth <depth> Specifies the maximum depth for the perft test. [default: 6]
--fen <fen> Specifies the starting position if other than the default. []
-?, -h, --help Show help and usage information
>Pedantic uci /?
Description:
Start the pedantic application in UCI mode.
Usage:
Pedantic uci [options]
Options:
--search <Minimal|Mtd|Pv> Specifies the search type to use. [default: Pv]
--input <input> Specify a file read UCI commands from. []
--error <error> Output errors to specified file. []
-?, -h, --help Show help and usage information
The evaluation currently evaluates the following positional features:Sorry, but both of those implementations are too strong for Pedantic at the moment. I am currently using Celestial 1.0 rated about 1700 to test against. My raw nps speed is around 2-3 times slower than Celestial which was developed in rust, so I have to adjust all my heuristics to minimize the number of nodes I actually evaluate. I thought that optimizing the evaluation would be the challenging part, but this entire process of tinkering with pruning, reductions, and extensions has had me pulling my hair out at times. Hopefully, Pedantic will be strong enough to test against your engines in the future.lithander wrote: ↑Tue Jan 10, 2023 11:43 amYou could play against earlier version like 0.4 (1890 Elo) or version 0.5 (2270 Elo) of MinimalChess of course. And you may want to try Leorik 1.0 which is also in the desired Elo range (2150) but has the interesting property that it does not implement any unsafe pruning techniques, reductions, extensions etc. Not even null-move pruning. This causes a high branching factor and the search remains quite shallow even at higher time controls. But it solves all mate puzzle with the shortest path for example because it never overlooks a move. This could expose some weaknesses in your engine if you overdo it with the pruning and reductions!
Yeah, I know exactly what you mean. For the first couple of months I basically tried to implement what I heard people talk about on the forums but without looking implementation details up. Narrow windows, and null move pruning and late move reductions and qsearch of course. Progress was relatively smooth and steady. But I didn't do much in terms of selectivity and when I ran out of ideas I thought I could just read up on all the specific extensions and reductions on the wiki and add some of them. But then nothing seemed to work. Maybe you can't add them one at a time but some of them have to go together? Or I did some fundamental error somewhere down the line and now my engine is too different? I couldn't figure out exactly why.
I still think there is black magic involved. I am almost ready to call in the local voodoo priestess!lithander wrote: ↑Wed Jan 25, 2023 1:21 pmYeah, I know exactly what you mean. For the first couple of months I basically tried to implement what I heard people talk about on the forums but without looking implementation details up. Narrow windows, and null move pruning and late move reductions and qsearch of course. Progress was relatively smooth and steady. But I didn't do much in terms of selectivity and when I ran out of ideas I thought I could just read up on all the specific extensions and reductions on the wiki and add some of them. But then nothing seemed to work. Maybe you can't add them one at a time but some of them have to go together? Or I did some fundamental error somewhere down the line and now my engine is too different? I couldn't figure out exactly why.
At this point I have looked at extensions both ways. I really need to get serious about setting up a test suite I can use to evaluate the benefit of these changes. Many of the changes may only benefit a minority of positions but without a good test I only have my hunches to lead me (which is probably a very bad idea.)lithander wrote: ↑Wed Jan 25, 2023 1:21 pm By now I've accepted that if I want to make progress with Leorik I shouldn't look too closely at what others are doing and be prepared to challenge what seems to be generally accepted. For example, why have both extensions and reductions? Why not have only reductions - which is an implicit extension of everything you don't reduce, right? Or when I look at how Stockfish get's to incredible depths so quickly... I don't know how they do that but certainly not by only pruning near the leafs. In the light of that calling it extended futility pruning because you start with the pruning at depth==2 instead of 1... well, seems like something from the 80s when search depth was much shallower. How about we *really* go and extend that?