Rodent IV beta

Discussion of anything and everything relating to chess playing software and machines.

Moderators: Harvey Williamson, Dann Corbit, hgm

Forum rules
This textbox is used to restore diagrams posted with the [d] tag before the upgrade.
User avatar
Graham Banks
Posts: 34676
Joined: Sun Feb 26, 2006 9:52 am
Location: Auckland, NZ

Re: Rodent IV beta

Post by Graham Banks » Sat Aug 31, 2019 9:31 pm

Gabor Szots wrote:
Sat Aug 31, 2019 11:53 am
Thank you Pawel for the Rodents you have given us. I have also enjoyed this background information very much. Good luck and much fun with your job!
Agree completely. :)
gbanksnz at

Posts: 42
Joined: Tue Apr 09, 2019 6:10 pm
Full name: mario varela

Re: Rodent IV beta

Post by camava » Sat Aug 31, 2019 11:41 pm

Rodent is my favorite chess engine to play against it. :D
I play every day in anywhere i have time(smartphone) i would like too much this iv beta versión with UCI_LimitStrength option(so i can play against it) like Rodent lll 0.171 this is the android version i have.
Rodent is for me the chess engine that plays the most diverse games when I play against it.
Thank you very much for this wontherfull chess engine sir.

Posts: 2027
Joined: Sat Jun 02, 2012 12:13 am

Re: Rodent IV beta

Post by carldaman » Sun Sep 01, 2019 4:12 am

Thanks a lot for all your great work with Rodent that you've shared with us all these years. A free program that delivers features not seen in most commercial software! I wish you continued success in your new endeavors. :)

Posts: 868
Joined: Mon Jan 15, 2007 10:23 am
Location: Warsza

Re: Rodent IV beta

Post by PK » Sun Sep 01, 2019 1:43 pm

A free program that delivers features not seen in most commercial software!
This is extremely puzzling to me. Everybody seems to remember popularity of Chessmaster franchise. Implementing personalities is not that difficult, as long as search can deal with asymmetric evaluation. Part of tuning can be "outsourced" to users, and some of them will even enjoy the process (hear me, Brendan J. Norman!). Different playing styles, and ability to tweak them, should be a huge selling point, and one that is independent from playing strength. Why nobody does that?

Posts: 22
Joined: Tue Jun 26, 2007 4:31 am
Full name: Charles Wong

Re: Rodent IV beta

Post by adnoh » Sun Sep 01, 2019 4:55 pm

Thanks for all of your work, Pawel.

I also wish more focus is placed on features and not just outright ELO chase. I am a weak chess player going back to Sargon days and also a fan of ChessMaster as I could fantasize myself going up against Tal. It is too bad seemingly for most people, definition of best is the strongest ELO.

I am looking forward to trying Honey from MikeB and the adaptive strength.

User avatar
Posts: 1338
Joined: Sat Nov 25, 2017 1:28 pm
Location: France

Re: Rodent IV beta

Post by xr_a_y » Sun Sep 01, 2019 5:25 pm

What a great engine Rodent is for learning about chess programming. Thanks a lot.

User avatar
Posts: 4405
Joined: Tue Jul 03, 2007 2:30 am

Re: Rodent IV beta

Post by Ovyron » Mon Sep 02, 2019 9:04 am

PK wrote:
Sun Sep 01, 2019 1:43 pm
Different playing styles, and ability to tweak them, should be a huge selling point, and one that is independent from playing strength. Why nobody does that?
Because it doesn't increase sales in practice?

Komodo 1.0 tried it and allowed people to create personalities with it and such, and it was ditched because it was clear customers didn't care much about it (or for those that cared, Komodo 1 was strong enough and stylistic enough to deliver at the time, so stronger versions for personalities wasn't necessary.)

In general, commercial developers have decided to rid their engines of configurable options for users. Learning was a major setting removed from commercial engines that used to have it, such as Rybka, Houdini and Shredder. What I gather is that adding more options does not increase sales, and removing options doesn't seem to decrease sales, so we only have to blame the people with the money interested in chess engines for what they buy, that dictates what options are kept or added, and engine personalities doesn't seem like one of them.

Except this also affects free engines as well, just look at Stockfish 14051722's settings:


Believe it or not, these few parameters were enough to "have fun" and change the playing style of the engine "drastically" (relative to other Stockfishes.)

So, how did the very next version look like?


BAM! Overnight, something of value was lost, and... I think it has been difficult to find someone else that knows or cares about this, because Stockfish is an engine used by people looking for strong moves, and any tweaking of those settings would only make it weaker. While people that didn't care about strong moves and only style were focused on engines that could be tweaked further, such as Rodent. But I reckon Stockfish 14051722 with Pawn Structure = 0 and Aggressiveness=200 was the most stylistic engine from this codebase, even surpassing the best Glaurung.

My dream is that one day someone comes with a tool to "equalize" chess engines, so that they all have a performance of 50% against each other, and then we'll be able to see the actual chess being played regardless of how "weak" they play, and it'll manage to show their true playing style, and we'll be able to compare them. And only then, we'll be able to know if Rodent or some other engine has the most exciting one, and if tweaking the parameters can create the ultimate chess entity that would blow us away with its moves every single time it plays, but not necessarily because they're strong.

Like so many things, it seems I jumped on the ship right as it was sinking. Hopefully the main reason for finishing the project is boredom, and one day you can come back with a new engine, with beautiful source code, that leaves the Rodent project in shambles, by comparison.
Your beliefs create your reality, so be careful what you wish for.

Posts: 868
Joined: Mon Jan 15, 2007 10:23 am
Location: Warsza

Re: Rodent IV beta

Post by PK » Mon Sep 02, 2019 10:28 am

As of usability of options, it comes in two flavours, for power users and for casual players. Most of Chessmaster users were probably perfectly content with picking predefined opponents, but to have them, somebody needs to tweak them first. Had the Komodo team given us Komodo Tal and Komodo Petrosian, just two styles for maximum contrast, alongside with the raw options, it would probably work money-wise.

As for Stockfish, disappearance of stylistic options was definately a wrong turn, and I said that much at the time. Agressivenes/Cowardice was in Shockfish since Glaurung days, and was worth keeping. This parameter pair, and the fact that they were asymmetric, inspired me to start adding personality parameters to my engine. After adding asymmetric mobility, core of personality system has been formed. Mind you, you can have four distinct types: attacker (own attack and own mobility raised), my favourite constrictor (own attack and opponent mobility raised), defender (opponent attack and opponent mobility raised, difficult to tune, as it usually needs some compensation in other parameters to have any agenda of its own) and a funny type with own mobility and opponent attack raised, that tries to keep the other player busy.

Nowadays, I read Stockfish like a book, because it contains plenty of beautiful engineering stuff, but I don't use it much as an engine. It could be printed on paper for me.

I don't think that boredoom is the right reason for abandoning Rodent. It is rather excess. I still enjoy writing chess engine, or tweaking somebody else's checkers engine, at work.

Posts: 2357
Joined: Sun Feb 07, 2016 11:43 pm
Full name: Brendan J Norman

Re: Rodent IV beta

Post by BrendanJNorman » Mon Sep 02, 2019 3:30 pm

mesilikas wrote:
Sat Aug 31, 2019 1:10 pm
The 2 big R's in computer chess: Rodent and Rebel! Thanks Pawel for the one of them!
+1 My favorite two engines, actually - forget Elo.

Posts: 419
Joined: Wed Sep 30, 2009 3:30 am

Re: Rodent IV beta

Post by Dayffd » Mon Sep 02, 2019 9:16 pm

At one point toward the end there was some mention of how it is seldom that engines are tweakable any more when released, with an example by ovyron mentioning Stockfish 14051722 specifically pointing out that the very next version did not have parameters that could be change. Just to toss in a mention, I have been tweaking these parameters for some engines, e.g. Deep Junior 11.1, 11.2, Little Goliath of different flavors, Glaurung 1.2.1, sting, Shredder, Nimzo, stockfish 5, and others naming them for instance D. Junior 11.1 Coffee House 1, etc. I do have one setting for stockfish 5 (Fury) that not only plays what seems to be an interesting, game but has some decent results, scoring 4 - 0 against Sting 10. Other engines are not quite as successful, though. :)
David S.

Post Reply