## Thursday, December 13, 2007

### What does a pawnmove do?

While investigating pawnmoves I'm impressed of the effects of a single pawnmove. It is much easier to calculate the effects of the move of a piece than of the humble pawn. What does a pawnmove do?

The effect of a single pawn move is felt in 3 area's:
• Opening and closing of diagonals
• Opening and closing of files
• Giving up the control of squares while getting the control of new squares
Take for instance the following simple move forward:

The move e4-e5 opens two diagonals. If this is beneficial or not depends on who's bishop is on those diagonals.

At the same time another set of diagonals is closed. Assuming that the pawn is well defended on the new square. If the closing of the diagonals is beneficial or not depends on who's bishop is on those diagonals. In general can be said that the white squared bishops have become more active while the black squared bishops have become less active.

Moving the pawn loses the control of d5 and f5 while it acquires control over d6 and f6. This control must be deemed by the possibility to maintain an outpost on those squares. If this is beneficial or not depends on who can maintain an outpost on those squares.

If white takes on d5 there isn't only the usual effect on the diagonals and the squares, but it effects the files too.

For white the e-file is opened while for black the d-file has become open. Again, if this is beneficial or not depends on the one who can make use of the open file.

Summarizing.
A pawn move effects the activity of the knight (squares), bishop (diagonals) and rook (files). The criterium for a pawnmove is if it improves the activity of your pieces relatively to the activity of your opponents pieces.

1. In a recent thread someone asked, "What's the trickiest piece?". Most people said the knights, but Loomis and I picked the pawn. Tricky little buggers! Our choices in the opening about whether a pawn should stay, advance, or exchange haunt us well into the middlegame and sometimes even into the endgame. Good article.

2. Excellent summary I wish I had my hands on two years ago! This is something it will be nice to review before games.

Wouldn't it be cool if we could move pawns backwards? How about we get a get out of jail free card, one per game, and when we play it we get to move one pawn backwards that we have already pushed.

3. LF,
it becomes even trickier when there are other pawns involved. When one move leads to contact with other pawn(s).

4. Blue,
I wish I knew this 10 years ago:)

5. Great stuuf.

A small note:
At the same time another set of diagonals is closed. Assuming that the pawn is well defended on the new square.
True. But often, if the pawn is well defended it is defended by another pawn, so there was already another pawn on one of the diagonals. But everything you said is still accurate as this can be the difference between a lonely pawn (target) on a diagonal and a pawn chain (closed!) on a diagonal....

6. Glenn,
I was well aware of that. I left it out for a pedagogical reason. I didn't want to make things too complex right away. But you are perfectly right. The diagonal is closed for your own bishop, but not necessarily for your opponents bishop.

The main point (thx Glenn that you give me a chance to repeat it) is that there is an objective criterium for pawnmoves: what is the impact on piece activity.

7. Good stuff Tempo.

As the great Philidor said:
"The pawn is the soul of chess."

8. Tempo, nice post, I see your pawn studies are bearing fruit.

Although this does give us some criteria to munch on while pawndering a push, I would hardly call the impact on piece activity objective, especially when it involves several pieces at once, as there are usually several conflicting but equal evaluations. It may limit your opponents activity for the short run but allow him greater activity in the long run for instance.

9. Drunk,
in the opening and the middlegame there can be no other reason for a pawnmove than its impact on the piece activity of both sides, the relative piece activity, so to speak. Or can you think of another reason? Of course we are not speaking about promotion here.

10. Simple. Complex. Paradoxical, even :P

11. A very nice chess lesson

12. Becuase we can't undo a pawn move by going backwards we need to proceed with caution when pushing. Sometimes a pawn push may free up our bishop on one diagonal, but on the other hand we give up control of a square that the opponent now uses for an outpost square for a pesky knight. Care must be taken when we push a pawn.

13. Good article (except for the numerous grammar & spelling inaccuracies).
With all the talk of diagonals & files, no one mentioned ranks. When you move a pawn, you open a rank & close another rank, (except for rook pawns) sometimes this matters.