|Diagram 1. White to move|
This is a position where my mind wanders around for quite some time. With trial and error the wrong cues are triggered first. I have done an awful lot of analysis on this kind of positions. And although that often leads to a deep understanding of the specific position at hand, it usually doesn't yield anything that goes beyond that very position. The reason for that is, that the positions differ so much. Chess is such a rich game, that no game resembles another. And even the tactical combinations are extremely rich. Which is the main reason we don't come any further, even after hours and hours of analysis of a position. The analysis doesn't transfer to other positions.
The geometry coat hook
The coat rack is intended to go beyond that limited application. Geometry is our next hook. The straight line is the most prominent geometric property of the pin. As Robert pointed out, a line is a distinct feature of other duplo attacks as well, like a skewer, roentgen attack, the discovered attack and a subset of the double attacks. Rooks, bishops and queens all move in straight lines. Only the knight limps in a strange way over the board, which probably means that a knight should have his own geometrical system.
That justifies a closer look at the line. Lines come in different flavors. With or without targets and/or attackers on the line. Presumably we should start with the most simple situation, there where an attacker and a target are already in place.
Which cue should fire in the position above? What should the implanted Robert Coble chess module shout in our ear? I think if it would shout c8!!, I probably would solve this position must faster.
Both the attackers Rc2 and bishop h3 bear down on c8. As Robert pointed out, a line of attack which is blocked by pieces (or pawns) gives you a glance into the future. I posted about the relationship of time and geometry long ago. There are a lot of pieces that stand in the way between the attacker and the target. If you can move them (own piece) or force them (hostile piece) out of the way, then all of a sudden c8 is outnumbered (encircled). The bishop on c8 is an important defender of Nd7 (function). This seems to imply that I must add to other coat hooks: encircling and function.
Now we have:
- Target placement
- Exploiting immobility
- Opening of the line of attack
- Connection to other tactical themes
- c8 is outnumbered (encircled)
- Nd7 has as function to block the line of attack between Bh3 and c8, so it is pinned
- This means that Nf6 is not defended by Nd7 (Nd7 is immobilized by another function)
- Bc8 is not yet immobilized by its function to defend Nd7, but after Bxf6, it is
Only geometry guides my attention towards c8.
Encircling tells me that c8 is outnumbered. Not yet, but in the future.
Function tells me that c8 and d7 are immobile because of their obligations.
Encircling tells me that d7 is BAD (Barely Adequate Defended) after Bxf6
Function tells me that Nf6 defends d7
The other hooks like Value, Defenders and Exploiting immobility are closely related to the three motifs of Lasker. The clues lead to the cues.
The other tactical themes like the knightfork and the discovered attacks play a minor rule. When their cues fire we get distracted from what is really important. I'm going to have a closer look at the motifs of mister Lasker. So now we have a tree in stead of a coatrack.