# Computer Chess Club Archives

## Messages

### Subject: Re: Rybka - How much Fruit is inside ?

Author: Uri Blass

Date: 19:20:57 12/11/05

Go up one level in this thread

```On December 11, 2005 at 20:59:08, Daniel Mehrmannn wrote:

Sorry but I do not understand your proof
I am not good at reading source code of other people but if I understand
correctly you had to change numbers in the tables in the source that you give
to produce output similiar to fruit.

The idea to have rook mobility based on number of moves is obvious but I do not
see the same evaluation as fruit in your code

for example it seems that your code evaluates rook mobility as less important
and also has a different piece square tables:

>-static const int RookUnit = 7;
>+static const int RookUnit = 6;
>-   P(piece,D3,Opening) += 10;
>-   P(piece,E3,Opening) += 10;
>+   P(piece,D3,Opening) += 15;
>+   P(piece,E3,Opening) += 15;
>+   P(piece,G2,Opening) += 10;
>+   P(piece,B2,Opening) += 10;
>+   P(piece,G7,Opening) += 10;
>+   P(piece,B7,Opening) += 10;
>+
>+   P(piece,C4,Opening) += 2;
>+   P(piece,C5,Opening) += 2;
>+   P(piece,D6,Opening) += 2;
>+   P(piece,E6,Opening) += 2;
>+   P(piece,F4,Opening) += 2;
>+   P(piece,E3,Opening) += 2;
>+   P(piece,F3,Opening) += 2;

>Hello,
>
>I was long thinking if i really should post that and some people giving me
>warnings
>to not do that, but i think i must do that to feel better.
>
>First, don't understand me wrong, i _dont't_ say Rybka is a Fruit clone, but i'm
>asking how much Fruit is inside this engine ?
>
>Well, i tested a lot of positions and games and my result is that Rybka using at
>least the PST-Tables and mobility of Fruit. Of course the author has added a lot
>of additional own stuff, but basicly he's building his engine on fruit functions
>or ideas.
>I have no problems if someone using other ideas of programms. But i have a
>problem if it so clear, in this case so much, and such engines go commercial.

In this case you should have problem with every commercial program.
A lot of programmers use the same ideas(for example a lot of programmers use
null move pruning)

Fabien himself has no problem with using fruit's ideas.
The only thing that is not allowed is using copy and paste.

Uri

```