## Friday, February 22, 2013

### A closer look at a combination

The KNpKN endgame showed me the way how to learn from a chess position in a definite way. That's why I have another look at a tactic from my database. A tactic I failed, lately. I realize now that I haven't dug deep enough in this position. I will try again, in order to see if I can get the same clarity as in the KNpKN endgame. This is the position:

Black to move. You can find the solution here.

Let's inventorize the basic elements first.

Element 1: Discovered attack
The move 1. ... c3+ is a discovered attack with as target the king and the bishop. The bishop on f1 is outnumbered.

Element 2: Discovered counter attack
After the move 2.Rxc3 the following counterattack reveals itself:
White can take the black bishop with check. It's a pity it's black to move. Yet black has to reackon with it.

Element 3: Counter attack hanging piece.
After the move 2.Rxc3 the following counterattack reveals itself:

White can take the haning black rook at c7. It's a pity it's black to move. Yet black has to reackon with it.

After the move 2.Rxc3 the white king is overloaded.

Element 5: pin

After the move 2.Rxc3 the white bishop is pinned against the rook since the rook is unsufficient protected due to an overloaded king.

Element 6: annihilation of the defender.
After 1. ... c3+ 2.Rxc3 Rh2+ the following position is reached:

The king is threatened. But it defends the rook on c3, so the king can't move.

Element 7: another pin.
After 1. ... c3+ 2.Rxc3 Rh2+ 3.Be2 the following position is reached:

The bishop is pinned against the king, so at least one counterattack (Bxb5+) is ruled out.

After 1. ... c3+ 2.Rxc3 Rh2+ 3.Be2 the following position is reached:

Element 9: another discovered attack.
After 1. ... c3+ 2.Rxc3 Rh2+ 3.Re2 Bxe2 the following position is reached:

The threat Bxf1+ is another discovered attack.

Element 10: and yet another overloaded king.
After 1. ... c3+ 2.Rxc3 Rh2+ 3.Re2 Bxe2 4.Bxe2 the following position is reached:

And the white king is overloaded again.

Order of the elements.
Any combination in this position is made by combining these 10 elements. The elements themselves are basic, trivial, well known and easy to spot. Yet it is not so easy to work out the right order OTB. The mind is easily blurred by the sheer number of the elements. Especially the possible counter attacks add to the confusion.

That's why I want to have a closer look at this position. Maybe it's difficult to find the whole sequence at once. But maybe that isn't necessary. Maybe we can say something about the priority of the elements in every position. We are on the look out for ideas that are transferable from one position to the next.

The rule of the initiative.
One thing that disturbs the mind is the initiative. Take for instance a look at element 3. The black rook on c7 is hanging. but since it is black to move, that is irrelevant. It can become relevant though, if blacks next move isn't forcing enough. A position cannot be judged without the knowledge who is to move. The pure geometrical pattern on the board isn't paramount at all. That is disturbing. Can we find some clarifying rules here? When can a counter attack be neglected?
A counter attack can be neglected when a move is higher ranked in the CCT index. When you give a check, it is irrelevant that your opponent can capture your queen if he were to move. If you capture a queen, it is irrelevant that he can take a rook the next move. If you take a rook, it is irrelevant that he can threaten your queen the next move. Since a threat is no capture. If you capture a rook and he can give a check though, it is a different story. Since the check is higher rated than the rook capture, you hand over the initiative to your opponent. When that happens, the counter attacks of your opponent need to be taken into account.
Let's have a look at our position after 1. ... c3+ 2.Rxc3

Black to move.
It's logical to think first about cashing in the outnumbered bishop at f1 by immediately trading the rook on c3. But there is a problem with 2. ... Rxc3. You should ask yourself here: "has white a move with a higher CCT index than my Rxc3?" It turns out he has. 3.Bxb5+ with check! This hands over the initiative to your opponent. Only now you need to look at the counter attack of your opponent (element 2 and 3). In this case it is over fast. The discovered attack with check brings in a bishop and a rook for white. I failed this position since I missed that 3.Bxb5+ was with check, btw.
This means that the most logical move 2. ... Rxc3 isn't high enough ranked in the CCT index. The only reason to think further is when there is a higher ranked move than Rxc3. It turns out that there is: 2. ... Rh2+

A hypothesis to be tested.
Do we need to know all 10 tactical elements before we can decide to make a move? Before I wrote this post I was inclined to say "yes". But my experiences with the KNpKN ending casted doubt on this conclusion. Now it seems sufficient that we only see the tactical elements in the current position. With current I mean the position that is currently under investigation, whether that is the position that is actually on the board or an imaginary position in the future.
In practical situations, the mind is blurred by messing up the different future positions with the actual position. Can we safely escape from that by a ridgid application of the rule of the initiative? If so, it would rid the mind of a vast lot of ballast. How often do we say: I saw what tactical elements played a role, but I messed up the move order? Our probing mind with it's trial and error approach seems to work counterproductive here. I'm going to test this idea, in order to see if there are exceptions to the rule of the initiative.

1. This situation is much easier than OTB, we already know there is a tactic and there is no other idea than c3+. But careful, such a tactic dont need to work in real life.
There is only the question remaining: if c3 imediatly or after an other move.

C3+ is a double attack, King and Bishop are "hanging".
It "works" because the count on the bishop is 0 and the king is notorious weak.

After c3+ black has the methods to treat double attacks. Move one of the attacked pieces (the king) to protect the other attacked piece dont work, but saving one piece from the attack and attack a higher valued piece at the same time does work. with Rxc3 black defends by attack. The amount of possible replies to a given situation is small. The question is not that much how ( wich tactical pattern we use ) but what method ( defend one piece and attack a high valued piece).

See endgamespecialist GM Averbakh : Chess Tactics For Advanced Players, Chapter: Defence against double attack.

The beauty ot this problem is that the method "make one piece unattacked and attack a high value piece" is continued. ( I did call that MegaFork and UnMegaFork. But this knowledge is very old )

I share the idea that there is much to see at the current position. I call the ability to get quickly aware of such "seeds of tactical destruction" a "view". But OTB this puzzle has to be calculated till the end ( IMO ).

2. @Aox,
But OTB this puzzle has to be calculated till the end ( IMO )

In my opinion too. When calculating, you hop from one position to another. Some elements are relevant to position A while other elements are relevant for position B.

In practice I experience the problem that I'm inclined to think about all 10 elements in all positions. Which leads to an overwhelmed mind.

This post is about an attempt to define the rules that must lead to thinking about the relevant elements only in any given position. It's about pruning the irrelevant thoughts safely.