Sunday, December 24, 2006

Brainstorming about piece activity

I expect no clear thread in this post, since I haven't made up my mind yet.

Piece mobility is defined as the number of squares you control. I love the simplicity of this definition since it is just a matter of counting. It says nothing about the quality of those squares though. That's why I think that piece activity is a better word to use for the things I'm talking about.

But what is the activity of a piece?
Just counting the owned squares isn't enough.
A rook at a1 can cover your whole backrank. Still it can be a very inactive piece. So activity has something to do with the enemy camp.
Just counting your squares at the enemy side of the board, seems to be an arbitrary choice.

A bishop can be good, bad or active.
A bishop is considered good when there are no central pawns which obstructs its activity.
A bishop is considered bad when the central pawns stand on its color thus blocking it.
An active bishop can be either good or bad; it is called active just because it performs some active function. Often the difference is if it is in- or outside the pawnchain.

A piece bound to defense is very restricted. Although it may cover a lot of squares, it cannot go there without losing material. A rook that attacks a pawn which is defended by a rook is called active, since it can go everywhere. The defending piece is called passive, since it hasn't that freedom. The moment the attacking rook moves somewhere else, the passive rook is released.
So the difference in mobility is decided by just one tempo. Hence the difference between active and passive can be decided by just one tempo.

A knight outpost is good when the knight is in the neighbourhood of the enemy king. So the activity seems to have to do something with targets in the hostile camp. It are not quite the same targets as we are used to in tactical problems. The king is a target, weak pawns are targets. Enemy pieces are just too volatile to be targets by non tactical means.
So in general: sitting ducks are the targets.

Sometimes, if black has a bishop at f5 and a rook at c8, black can penetrate via c2. Which becomes a new home for a black piece. So active pieces are strong when they work together.

In general: an active piece can have a host of potential new homes along it's open line from where it can be even more active.

Can there be an algorithm which expresses the activity of a piece?

Today's random chess quote at chesshere:

Michael Stean: The most important feature of the chess position is the activity of the pieces. This is absolutely fundamental in all phases of the game (opening, middlegame and especially endgame). The primary constraint on a piece's activity is the Pawn structure.


  1. "...activity of pieces...". So, not just one piece, but more pieces. I am expecting a new Temposchlucker-system on piece harmony soon now ;)

  2. Great topic. Activity seems to be a very thorny little concept. I wonder what the unifying idea behind activity is, i.e., what makes each instance of it, even those that look very different, instances of the same principle. Aristotle's essence...

    Perhaps it isn't a single concept but a cluster of related concepts that all have to do with potential initiative.

  3. Fier,
    in stead of making fun of me, some help on the topic would be. . .helpful:)

  4. Are you going to write a new chess software? In doing so, algorithms of piece activity would do a great job.

    Or have you, considering the recent success of Deep Fritz, in mind to turn your brain into a sort of bio-computer? Again, algorithms would do a great job.

    I am not saying that there is no use of algorithms besides these jobs. Beware, I'll never dare. But I just do not see it. Maybe you can help me.

    Just remember, I also had my algorithm times with my late target feature count which turned out not to be very helpful.

  5. Mouse,
    the search for algorithms is the search for simplicity. You are right that simplicity is seldom found in chess. As former computer programmer the question after algorithms is my the genes though. But even the answer to the question why no algorithm can be found is useful.

  6. Tempo, I guess that there must be lots of algorithms, but that they are so many that only computers can handle them. The reason for my guess is the non-linearity of chess. That is, change the position of a single piece by just one square, and you get completely different a picture, changing from win to loss to draw in a wild manner.

    Why not forget about algorithms and just look at the pieces? Knights must have safe outposts, Bishops must have open diagonals, Rooks must have open ranks and files, and all pieces must have targets to go for. And do not forget Kings! They must have dry, warm and safe homes except in endgames when they go for a fight. Is this not all very simple? Maybe the real problem is to tell which of all the simple things is the most important one.