Fruit chess engine license

However regarding playing strength they should be similar since no strength-related code has been changed. Answer: The books from Fruit are enginebooks. However Fruit will use the book if proper indicated in the Parameter "BookFile" and if the Option "OwnBook" is active both are the default values.

You can change the used book if you change the Parameter "BookFile". Unfortunately looking on the percentage of different book moves is not possible at the moment. But that would mean to create for each GUI a special book. You can check whether Fruit uses in fact the tournament book when you try to move the book. If Windows refuses the moving your book is being used. Once Fruit uses its book it always plays the best moves given the existing probabilities in this book.

Tournament directors will want me to designate an official book that they should use. It is in fact the same as "fruit. However, I would prefer that Fruit has access to a larger book during tournaments.

The reasons for my decision are: - the source code by Eugene Nalimov is not "free of use" although you don't have to pay for it - the design of the code does not work well with Fruit's "small memory footprint" requirement for example the executable file would be at least twice as large with the TB code. It must be said though that I have great respect for Eugene's contribution to the computer-chess community.

As for Fruit I plan on using selected "bitbases" in the very far future. For now some draws are recognised by the evaluation function, and - despite the errors - this somewhat reduces the penalty for not using tablebases.

UCI options You are advised to skip this section unless you are completely crazy about computer chess. Here I give you another chance to skip the section, as you should not be reading this Well you have downloaded Fruit in the first place so I suppose I can't do anything for you anyway I give up! Never use "Never" ever! OK you can use "Never" to test a Zugzwang problem, but ask your Momma first!

I expect that this option has little effect assuming the first two choices only. I only added it because most engines do not use the fail-high condition. It seems better than always using 2 though. I have not experimented with adaptive solutions. I expect it to hardly have any effect in games. The default value should be sufficient for most-common Zugzwang situations. Of course it means Zugzwang problems need a lot of depth to get solved, if ever! With such a reduction, verification search is similar to Vincent Diepeveen's "double null move".

I added it in Fruit 2. It should help in blitz, but it's possible it actually hurts play in longer games!!! One day, I should check this. One day Lower values are safer, and higher values more aggressive. There is a good chance Fruit's strength can be improved by changing this option. Makes the engine a tiny bit better at tactics but slightly weaker positionally. It might be beneficial by a very small amount, but has not been tested in conjunction with history pruning yet.

It could lead to problems in the endgame. Larger values prune less but will lead to fewer positional errors. Probably safer because it is used mainly during the middlegame. Has not been tested with history pruning either. This one is probably safe.

It could be interesting when solving mate problems though. You can modify Fruit's playing style to an extent or make Fruit weaker for instance by setting "Material" to a low value.

It also includes the bishop-pair bonus. I think "Pawn Structure" is not an important parameter. Who knows what you can obtain by playing with others? Note that Fruit is nowhere near ready to compete there because of the lack of xboard support and opening book. Note from the future: these limitations seem not to be a problem anymore.

Fruit 1. It is a very incomplete program, released "as is", before I start heavily modifying the code for good or bad. What you see is a picture of Fruit right in the middle of development. Fabien finished his commercial computer chess career so far in [5].

Fruit 2. Fruit was and still is one of the most influential didactic open source programs. It uses a 16x12 Vector attack board representation , since Version 1. Its structure and C source code was very clean and apparently bug-free due to runtime checking a lot of preconditions using debug asserts.

While late move reductions LMR might be used in other programs before, Fabien's history based implementation in conjunction with history leaf pruning made LMR very popular.

Another Fruit innovation, despite not absolutely new and already a known issue, and related to what is mentioned in evaluation philosophy , was tapered evaluation to avoid discontinuity [11].

Before he developed Gambit Fruit with some interesting changes on the basis of the last open-source-version 2. Joachim Rang was the main tester of Fruit since its first public appearance, tuned parameters, and tested evaluation and search features [12].