﻿ Stockfish 9 released

# Stockfish 9 released

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Thibault de Vassal    (2018-02-15)
Stockfish 9 released

It seems that Stockfish 9 is now available... Did anyone test it already?

Any improvement "noticed"? (seems hard to notice anything anymore :))

We'll see what rating it reaches on CEGT lists...

Garvin Gray    (2018-02-16 01:25:26)
Stockfish 9 released

Probably a bit early to ask if any genuine improvements are noticeable, since its just been released :)

One comment that I do remember from the recent Computer World Champs, where Houdini and Komodo made the finals, and Stockfish 8 missed out by a whisker, was that each of the programmers said that Stockfish did not convert some positions because it did not have as high a contempt factor as Houdini and Komodo.

So it is likely that for Stockfish 9, this is an area that the programmers have worked on.

Kym Farnik    (2018-02-16 09:21:20)
Stockfish 9 released

FYI Development builds now have dynamic contempt.

Author: Stefano Cardanobile
Date: Fri Feb 9 19:07:19 2018 +0100
Timestamp: 1518199639

Introduce dynamic contempt

Make contempt dependent on the current score of the root position.

The idea is that we now use a linear formula like the following to decide
on the contempt to use during a search :

contempt = x + y * eval

where x is the base contempt set by the user in the "Contempt" UCI option,
and y * eval is the dynamic part which adapts itself to the estimation of
the evaluation of the root position returned by the search. In this patch,
we use x = 18 centipawns by default, and the y * eval correction can go
from -20 centipawns if the root eval is less than -2.0 pawns, up to +20
centipawns when the root eval is more than 2.0 pawns.

To summarize, the new contempt goes from -0.02 to 0.38 pawns, depending if
Stockfish is losing or winning, with an average value of 0.18 pawns by default.