Nov 7, 2011

[Info] Yay me

Up to my 10th failed attempt at tuning my passed pawn eval.

The last attempt I wasted 20,000 games.

I have tables looking like this:

Rank: 1 2 3 4 5 6 7 8
Value: {0,10,20,30,60,120,150,0}

That is increasingly higher evaluation the closer the passer is to promotion.

This table can than be stretched in all kinds of directions during the tuning (increasing/decreasing all values, or increasing the differences between them) using two "knobs", so the table only needs two values to tune instead of six.

Now, I had reversed the values when preparing for the tuning... so instead of giving 150 centipawns for being one square from queening I gave it 10.

The tuning tried to compensate and the best it came up with was:

Rank: 1 2 3 4 5 6 7 8
Value: {0,-83,-60,-14,-9,17,25,0}

Quite good effort, but I find it hard to believe a 8 cp difference for 6th and 7th rank is optimal.

Fixed the problem and running the tuning for the 11th time. :)

3 comments:

Anonymous said...

CLOP should be able to tune all 7 values at the same time without too much difficulty.

Anonymous said...

All 6, in fact.

Jonatan Pettersson said...

Indeed, but this is just one of three tables I'm using.

The one in this post is the middle game table, then there's the end game table, and also a table that adds extra bonus for passer that can safely advance.

Add to that two variables for king distances from passers in the end game.

So the test is actually running with 8 parameters (two for each table, and two for the king distances).