TalkChess.com

A piece becomes more powerful the less pieces of lower value the opponent has.

Is this true? For example, the fewer minor pieces an opponent has (knights and bishops), the more powerful its rook becomes.

Testing seems to show this, but I am way too lazy to wait for the thousands of games I might need to prove this.

Mark

Perhaps we should organize a huge joint effort to address fundamental questions like this? If we all donate a week of CPU time to play 3500 or so 40/1' games, and 30 persons participate, we can do 100k games.

If we use top-engines, the Pawn-odds score is over 70% (i.e. a Pawn corresponds to a 20% excess score), and the standard error in 400 games is only ~2%. So we could measure 250 judiciously chosen piece combinations (all close to equality) to a precision of ~10 cP.

mjlef wrote:A piece becomes more powerful the less pieces of lower value the opponent has.

Is this true? For example, the fewer minor pieces an opponent has (knights and bishops), the more powerful its rook becomes.

Testing seems to show this, but I am way too lazy to wait for the thousands of games I might need to prove this.

Mark

No, there is no "rule" such as that one for a carbon chess player. However, it makes sense indirectly. A rook is stronger when there are useful open files. The more minor pieces present, the less useful may become because the open files can be controlled. For instance, a Re1 is not to great if you have a Bd6 and Bd7 that controls the access.

Miguel

mjlef wrote:Testing seems to show this, but I am way too lazy to wait for the thousands of games I might need to prove this.

Mark

What did you test ? I don't understand what you are talking about, how did you translate 'powerfull' in your engine eval() ?
You are talking about equal material positions right ?

HJ.

mjlef wrote: Is this true?

Maybe you can conclude a general rule which assure that, but remember what a grandmaster would answer you: "it all depends on the position!"

There are a lot of way of implementing this. My first attempt is just to count the number of opponent minor pieces. The fewer the opponent minor pieces, the larger the rook value becomes. For queens I count number of opponent rooks and minor pi9ecesm, but the minor pieces count twice since exchange with them is worse for the queen, so whatever squares they control are more significant and restrictuive for the queen.

So I guess "powerful" in my case means "worth more". So this means a R and pawns vs say Knight and pawns would be worth more than +2, where say in an opening, a R vs N difference would be worth less than this.

mjlef wrote:A piece becomes more powerful the less pieces of lower value the opponent has.

Is this true? For example, the fewer minor pieces an opponent has (knights and bishops), the more powerful its rook becomes.

Testing seems to show this, but I am way too lazy to wait for the thousands of games I might need to prove this.

Mark

If you consider that most chess engines score mobility by counting the number squares that a piece can go to, then your statement has some merit to it (as far this type of scoring goes). A mobile queen is better than a mobile knight.

Now, if you consider scoring mate patterns (see Ed Schröder's chess programming article, from which I copied a lot of ideas from), then it goes the other way. You have less likelihood of getting into positions of mate patterns if you have less pieces to make the necessary combinations. A KQ-KQ is a draw, while a KQRBPPP-KQRBPPP has a greater possibility of being a non-draw.