Answers.Body: <p>A really strong and great positional open source engine I have used is Rodent.  The last version was Rodent IV and is available at <a href="http://www.pkoziol.cal24.pl/rodent/rodent.htm" rel="noreferrer">http://www.pkoziol.cal24.pl/rodent/rodent.htm</a></p>
  <p>Of course Chess Programming wiki continues to be a good place to research and discover engines and the following link shows only open source engines.</p>
  <p><a href="https://www.chessprogramming.org/Category:Open_Source" rel="noreferrer">https://www.chessprogramming.org/Category:Open_Source</a></p>
  
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Answers.Text: The best part of Rodent IV is that it is tunable, which no other chess engines offers
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Answers.Body: <p>Stockfish 12 is objectively the best in the free engines that is publicly accessible.
  Estimated Elo ~ 3230. There is another engine mildly more powerful however I don't believe its available and the difference is negligible. Stockfish has good positional awareness, aggression etc can be tampered with for interesting outcomes.</p>
  <p>I look at Komodo Dragon as a strong closed source engine and the Armageddon feature where it treats draws as a loss is extremely good especially for training purposes.</p>
  <p>Reality of it is almost all engines out perform human players in positional awareness , tactical and strategic play. Its like comparing brands of paracetamol. All the same and any differences are so minute we'd never notice them.</p>
  
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Answers.Body: <p>There is a free engine called <strong>Spike 1.4</strong>, which in 2024 has still a CCRL-rating of a little above 3000 Elo and which is a partner engine of the free Arena GUI. This is not the strongest engine, but I mention it in relation with what you call 'chess knowledge' because it doesn't use a neural network and by reading the wiki of this engine (see link below) I read evaluation functions based on pawn structures, tactical motives, endgame mechanics etc. that I usually don't read in the descriptions of the strongest open-source engines, so I have to assume that this engine has more 'chess knowledge' than usual.</p>
  <p><a href="https://www.chessprogramming.org/Spike" rel="nofollow noreferrer">https://www.chessprogramming.org/Spike</a></p>
  <p>Because of the way engines work and calculate, I'm not sure that 'chess knowledge' is actually best for engines, the proof is that AlphaZero with its reinforcement learning is very successful - without specific chess knowledge in the case of Lc0; the only knowledge entered in the code was basically the rules of chess and that's it. But this only applies to NNUE-type engines or such engines that rely on persistent learning. Instead, you should look for engines that don't rely on such technology but are still very successful, like Shredder 13 or Hiarcs 15 engine - which are not free however, these must have a lot of implemented additional code other than pure Alpha-Beta search, killer heuristics etc. as they must have some constant criterias for their deep selectivity, pruning and other tree-cutting heuristics. For the Stockfish engine which is currently the strongest, there are derivative engines that <em>both work with NNUE and without</em>, like <strong>SugaR AI ICCF 2.5</strong> which has a ton of useful parameters you can change, and there are a couple more of these, likelywise one among the best you can get (if you use it right) is the free <strong>ShashChess</strong> engine which allows you to pick 'search personalities' or to switch a special MCTS function on or off for the search, but it's a NNUE engine trained by persistant learning, not a classical engine. For more flexibility you need to get a paid engine like Komodo/Dragon which has a serie of 'chess knowledge' that you can activate or deactivate in the engine parameters. <strong>Komodo 14</strong> is actually free, so get it and see what it does.</p>
  <p>Generally my experience is: Changing these parameters is not adding to the engine overall strenght but it can resolve positions where you expect certain answers to be given (which is not necessarily the same as perfect play) and yes, your so-called 'chess knowledge' could make a difference on rare occasions.</p>
  
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Answers.UserDisplayName: MikeTrans
Body: <p>Most open source chess engines with hand-tuned evaluations are known for their innovations on search (Fruit, Stockfish).</p>
  <p>I was inspired by HIARCS' generally more human-like play and the fact that neural network based engines like Leela suggest that we have more work to do when it comes to evaluation functions.</p>
  <p>The reason is that I'd like to apply the same evaluation functions in a chess engine that I'm working on.</p>
  <p>Which open source engines are out there are known for its deep positional understanding? Unfortunately, engines known for their positional understanding such as Shredder, HIARCS, and Komodo are closed source.</p>
  
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Comments.CreationDate: 2020-11-15T03:18:42.290Z
Comments.Text: What do you mean by "chess knowledge" when it comes to chess engines? I have never heard or seen anyone refer to Shredder, HIARCS or Komodo as having "chess knowledge", do you mean somethng like "positional understanding"? Obviously no engine has any chess knowledge in terms of what humans mean when they say the word, so you need to clarify what it is that you actually refer to here.
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Comments.CreationDate: 2020-11-16T01:49:35.433Z
Comments.Text: Likely LC0. LC0 NN has the most complicated evaluation functions.
Comments.UserDisplayName: SmallChess
Tags: <engines><positional-play><evaluation>
Title: Which open source chess engine has the most positional understanding?
ThreadText: # Which open source chess engine has the most positional understanding?
  
  (Asked by: username_0 on 2020-11-14)
  
  Most open source chess engines with hand-tuned evaluations are known for their innovations on search (Fruit, Stockfish).
  
  I was inspired by HIARCS' generally more human-like play and the fact that neural network based engines like Leela suggest that we have more work to do when it comes to evaluation functions.
  
  The reason is that I'd like to apply the same evaluation functions in a chess engine that I'm working on.
  
  Which open source engines are out there are known for its deep positional understanding? Unfortunately, engines known for their positional understanding such as Shredder, HIARCS, and Komodo are closed source.
  
  **Tags:** engines, positional-play, evaluation
  
  > **Comments:**
  > **username_1**: What do you mean by "chess knowledge" when it comes to chess engines? I have never heard or seen anyone refer to Shredder, HIARCS or Komodo as having "chess knowledge", do you mean somethng like "positional understanding"? Obviously no engine has any chess knowledge in terms of what humans mean when they say the word, so you need to clarify what it is that you actually refer to here.  
  > **username_2**: Likely LC0. LC0 NN has the most complicated evaluation functions.  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_3 on 2020-11-16. Score: 5
  
  A really strong and great positional open source engine I have used is Rodent. The last version was Rodent IV and is available at <http://www.pkoziol.cal24.pl/rodent/rodent.htm>
  
  Of course Chess Programming wiki continues to be a good place to research and discover engines and the following link shows only open source engines.
  
  <https://www.chessprogramming.org/Category:Open_Source>
  
  > **Comments:**
  > **username_4**: The best part of Rodent IV is that it is tunable, which no other chess engines offers  
  
  ---
  
  ### Answer by username_5 on 2020-11-16. Score: 1
  
  Stockfish 12 is objectively the best in the free engines that is publicly accessible.
  Estimated Elo ~ 3230. There is another engine mildly more powerful however I don't believe its available and the difference is negligible. Stockfish has good positional awareness, aggression etc can be tampered with for interesting outcomes.
  
  I look at Komodo Dragon as a strong closed source engine and the Armageddon feature where it treats draws as a loss is extremely good especially for training purposes.
  
  Reality of it is almost all engines out perform human players in positional awareness , tactical and strategic play. Its like comparing brands of paracetamol. All the same and any differences are so minute we'd never notice them.
  
  
  ---
  
  ### Answer by username_6 on 2024-06-13. Score: 0
  
  There is a free engine called **Spike 1.4**, which in 2024 has still a CCRL-rating of a little above 3000 Elo and which is a partner engine of the free Arena GUI. This is not the strongest engine, but I mention it in relation with what you call 'chess knowledge' because it doesn't use a neural network and by reading the wiki of this engine (see link below) I read evaluation functions based on pawn structures, tactical motives, endgame mechanics etc. that I usually don't read in the descriptions of the strongest open-source engines, so I have to assume that this engine has more 'chess knowledge' than usual.
  
  <https://www.chessprogramming.org/Spike>
  
  Because of the way engines work and calculate, I'm not sure that 'chess knowledge' is actually best for engines, the proof is that AlphaZero with its reinforcement learning is very successful - without specific chess knowledge in the case of Lc0; the only knowledge entered in the code was basically the rules of chess and that's it. But this only applies to NNUE-type engines or such engines that rely on persistent learning. Instead, you should look for engines that don't rely on such technology but are still very successful, like Shredder 13 or Hiarcs 15 engine - which are not free however, these must have a lot of implemented additional code other than pure Alpha-Beta search, killer heuristics etc. as they must have some constant criterias for their deep selectivity, pruning and other tree-cutting heuristics. For the Stockfish engine which is currently the strongest, there are derivative engines that *both work with NNUE and without*, like **SugaR AI ICCF 2.5** which has a ton of useful parameters you can change, and there are a couple more of these, likelywise one among the best you can get (if you use it right) is the free **ShashChess** engine which allows you to pick 'search personalities' or to switch a special MCTS function on or off for the search, but it's a NNUE engine trained by persistant learning, not a classical engine. For more flexibility you need to get a paid engine like Komodo/Dragon which has a serie of 'chess knowledge' that you can activate or deactivate in the engine parameters. **Komodo 14** is actually free, so get it and see what it does.
  
  Generally my experience is: Changing these parameters is not adding to the engine overall strenght but it can resolve positions where you expect certain answers to be given (which is not necessarily the same as perfect play) and yes, your so-called 'chess knowledge' could make a difference on rare occasions.
  
  
  ---
  
  