Tuesday, March 31, 2015

Calculating Forcing Moves: Defensive Idea 5 (Counterattack) - Equal Threats

I am very glad to announce that I have figured out how to embed positions from chess.com into blogger!!  This will be my first post trying this out, so please let me know what you think and bear with me if it doesn't work quite right.

In my last post I gave an overview of the 5th defensive idea, counterattacking.  All counterattacks begin by creating an equal or greater threat (EGT), and there are three distinct goals when conducting a counterattack: to win, draw, or to defend.

In this post I'll  explore the idea of creating equal threats which is important to understanding greater threats, because not all equal threats are actually equal.  There are three elements to understanding an equal threat:  the value of the pieces, whether they are defended/undefended, and tempo (turn to move, capture-checks, or other intermezzos). This all seems very simple until you add all three elements into one position, and suddenly the position becomes exceedingly difficult to calculate. So pay attention...you'll need to know this later!!

First let's consider value.  To create an equal threat you need to consider the value of both pieces involved in the threat.  Let's start simple.  Say a pawn is attacking your queen.  An equal threat would be to attack your opponent's queen with one of your pawns:

So far so good. But now let's look at how the next element impacts value, which is when the piece you are counterattacking against is defended.  Like in the above example, since both queens were undefeneded it actually did not matter what we used to counter-attack.  However, when the target piece is defended the value of piece you use to counterattack becomes VERY important.  Take the following position.

Like the first position, the white queen is attacked by a pawn and white can counterattack against the black queen using his pawns (on f3 or h3) or his knight.  If the black queen was not defended, it wouldn't matter which piece white chooses.  However, since the black queen is defended the value of your counterattacking piece is extremely important!

Now let's add in the final element of tempos.  Here we have three key elements of tempo (time) that impact counterattacks:  turn to move, capture-checks, and intermezzos.

There might be a better way of explaining this (I haven't seen it explained very well anywhere else), but the idea "turn to move" is that after the first set of captures there are more captures on the board, or some sort of tactic.  Here is a simple example:

Again, white's queen was attacked by a pawn and, since the black queen was defended, he counterattacked with the same value piece (pawn, instead of knight).  However, after the queens came off the board it was BLACK's turn to move and he simply captured white's knight!  Always keep this in mind when considering equal counterattacks -- if you're the defender, just remember it will be your OPPONENT's move after the initial captures.  I'm interested in reading Victor Charushin's book The Steeplechase to see how he treats this issue.

The next tempo element is capture-checks.  Capture-checks can occur at any point in a sequence of moves, and it is extremely important to remember that after you (or your opponent) use your move to deal with the check, it goes back to being your opponent's move again.  Use this to your advantage and make a point of noting and prioritizing capture-checks in your calculations.  Here's another simple example to demonstrate the idea:

Here white's queen is attacked by black's knight and, since the black queen is defended, he tries to create an equal threat by attacking black's defended queen with an equal valued piece.  But due to the capture-check, white only has time to deal with the check and has no time to follow through with his own counterattack!

The final element of tempo is intermezzos (also known as "zwischenzug", or in-between moves).  This is when your opponent is able to get out of the threat you created by creating another, more powerful threat, thrown in the middle of your variation.  It is essentially a counterattack.  Here are two simple examples using our topic of equal threats:


Here we have the same position from the beginning of this post where the white queen is attacked by a black pawn, and white creates an equal counterattack against black's queen with his own pawn. But this time black plays the in-between capture check (Qxg2+) winning white's pawn, before capturing the queen. This type of move is also called desperado, which is when you have a piece that is going to be captured and "sacrifice" the piece for the most valuable piece you can.  In this case the important issue is time, so the even though the pawn on g2 is not worth much, the time gained from the check is what is truly valuable.  [Thanks Tomasz for pointing that out!]

This next position shows another simple example of an in-between move:


Here again we have the same position from the beginning of this post where the white queen is attacked by a black pawn, and white creates an equal counterattack with his own pawn...only this time he chose the wrong pawn and black played the in-between check, moving the queen to safety, before taking white's queen.

The last position I'll share combines all three ideas of creating an equal counterattack (value of the pieces, defended targets, and time).  Enjoy!!


Wednesday, March 11, 2015

Calculating Forcing Moves: Defensive Idea 5 (Counterattack) - Overview

Of the five defensive ideas, counterattacking is by far the most interesting and the most exciting.  But at the same time, it is the riskiest and most complicated type of move in the game.  Counterattacks require you to leave a piece en prise, or leave your king exposed to a mate threat, while you fuss around with some other part of the board.  Ignoring your opponent's threat and launching your own equal or greater threat not only takes guts, but also requires solid calculation skills.  You must be able to calculate the consequences accurately or you risk losing the game or spoiling a better position.

There are three distinct goals when conducting a counterattack:  win, draw, or defend.  I will elaborate on each of those ideas in future posts.  In this post, I'll focus on the one idea that is common to all three goals, which is that all counterattacks begin with an equal or greater threat (EGT).

Searching for moves that create an EGT is what starts all counterattacks, and often involves one-upping the threat your opponent just created:  "You threaten my rook?  Yeah, well I threaten your queen."  As with all forcing moves, as the severity of the threat increases the number of options decreases.  Here is a very simple chart to demonstrate the idea:

The chart shows that:
  • When in check, counterattacking is simply not an option (it is illegal).
  • When there is a mate threat, you can only begin a counterattack with 1 type of move -- check.  You can't counter a mate threat with your own mate threat unless it starts with a check.  This also assumes that the mate threat is completely forcing, ie, there are no "pauses" during the sequence that give an extra tempo to defend.  The more "pauses", the more defensive options.
  • A threat against your queen can be countered with 1 equal threat (against the opponent's queen) and 2 greater threats (check, or a mate threat), for a total of 3 types of counterattacks.
  • And on down the scale of threats until you get to least threatening threat -- capture a pawn -- against which there are 17 different counterattacking targets to consider.

Threats can be more complicated than in this chart.  As you grow in skill you will be able to identiy and understand more complicated threats like moves that improve/decrease activity, threats to simplify to won endgames, more complicated material imbalances, better minor pieces, more sophisticated mating patterns, etc.  You are simply expanding the types of threats you know how to assess, but the EGT logic described here still applies.

The next posts in this counterattack series will cover four topics:  complications of equal threats, and the three goals of a counterattack (win, draw, defend).



Tuesday, March 3, 2015

Calculating Forcing Moves: Defensive Idea 4 (Defend)

When your opponent creates a (real) threat, or you are considering creating one against your opponent, there are five defensive ideas to consider.  We have already looked at different ways to implement the first three defensive ideas:  Idea 1 (capture the attacking piece, pin the attacking piece, deflect the attacking piece), Idea 2 (block the attacking piece), and Idea 3 (move the piece being attacked).  This post will explore the fourth basic idea of defending the piece being attacked.

This is another pretty straight forward idea -- your piece is being threatened and you find other pieces that can move to defend it.  This usually happens when the piece is loose (or just underdefended) you don't want to or can't move the piece for some reason.  The search method is simply to look for other pieces/pawns that can move to defend the piece.  Add those specific moves to your candidate list to calculate further.

The idea of capturing/defending brings up another important element of piece safety -- counting.  In its simplest form, the "count" is the number of attackers vs the number of defenders.  However, in addition to the simple quantity of attackers/defenders, there are also issues of quality, which may trump quantity, order of recaptures, and also captures on several squares.  This is a topic for another entire blog series, but it is very important to know the basics anytime you are considering defending a piece that is being attacked, and is hugely important when considering counterattacks (which we'll look at later).

Let's start out with a simple position to demonstrate the idea.  The general process is to evaluate the position, identify and prioritize all threats, and then use the five defensive ideas to identify specific candidate moves.  Next, calculate each candidate move to the end and evaluate the final positions (material and activity).  As you progress through the candidates, keep in mind the "king of the hill" (KOTH) candidate move to help you pick the best at the end.

Black just played Qf5 attacking White's rook.  White to move.

2kr4/1pp2p2/p4p2/5q2/4RP1Q/P1P3PR/1P6/1K6 w - - 0 1

Let's evaluate the position and then find all of white's threats.  White is up an entire rook, and black has no clear compensation.  White is playing to win, while black is fighting for a draw.  Black's immediate threat is to capture white's rook with the capture-check Qxe4+, restoring the material balance, and black will be slightly better because of his more actively-placed pieces.  Black has no other threats.  If white can keep his rook, he is clearly winning.  Let's look at the five defensive ideas to see what candidate moves we find, and then pick the best move.

Idea 1 (capture, pin, deflect):  no captures; 1. Qg4 pins the queen to something more valuable, but it is unsafe.
Idea 2 (block):  none.
Idea 3 (move):  none -- the rook is pinned to the king and cannot legally move.
Idea 4 (defend):  searching the board it is not immediately clear if white has any mvoes that defend the rook.  It is tricky to find, but it is there!  Highlight to see the answer: [1. Qh7.]
Idea 5 (counterattack with an equal or greater threat to WIN, DRAW, DEFEND):  an equal threat would be to win black's rook for nothing, but that is not possible here.  A greater threat would be to attack the queen or the king, but there are no checks and we've already considered 1. Qg4.

The tricky part of this position is not the calculation, so I'll skip further analysis since white is now clearly winning.  If you couldn't find the move (but you did look), try training positions using the x-ray theme until you never miss them again.  This idea is very important to remember -- if you find that you are "missing" moves, try to really understand if you missed them because you didn't even look, or you looked but didn't see.  Those are very different problems to have, but both can be trained.

This is the last blog covering the basic four ideas.  The next blog series will cover the very exciting and complex fifth idea of counterattacking!

Monday, March 2, 2015

Calculating Forcing Moves: Defensive Idea 3, Part 1 (Move)

When your opponent creates a (real) threat, or you are considering creating one against your opponent, there are five defensive ideas to consider.  We have already looked at different ways to implement the first two defensive ideas:  Idea 1 (capture the attacking piece, pin the attacking piece, deflect the attacking piece), or Idea 2 (block the attacking piece).  This post will explore the third basic idea of moving out of the attack.

The idea is straight forward -- your piece is being threatened and you find other squares to move to where it is not threatened.  This usually happens when the piece being attacked is more valuable than the piece doing the attacking.  The search method is simply to look for squares the piece can move to, and add those to your candidate list to calculate further.

Moving your piece out of the attack is often the safest, least complicated, and easiest type of move to find and to calculate.  The simplicity of this idea gives us the opportunity to look at another aspect of piece safety and calculation, which is considering your opponent's response even in quiet looking positions.  We'll look at a simple position that demonstrates this very clearly.

But like everything in chess, there are complexities.  There are times when the piece being attacked has important defensive duties and shouldn't move, has nowhere to safely move to, or simply cannot legally move because it is pinned the king (or something more valuable).  This brings in several entire families of tactics -- pins, remove the guard, trapping, mating nets -- and those complexities are a topic for another blog series!

The other element of this idea I do want to explore in a future post is "preparing to move".  These moves are possible when the threat is one move away, and you have time to move another piece out of the way so that you can escape to, or through, that square when the threat is played.

Let's start out with a simple position to demonstrate the basic idea.  The general process is to evaluate the position, identify and prioritize all threats, and then to use the five defensive ideas to identify specific candidate moves.  Next, calculate each candidate move to the end and evaluate the final positions (material and activity).  As you progress through the candidates, keep in mind the "king of the hill" (KOTH) candidate move to help you pick the best at the end.

White just played Kd4 attacking Black's rook.  Black to move.

6k1/6p1/6Np/p1r2P2/P2K4/2P5/8/8 b - - 0 1

Let's evaluate the position and then find all of white's threats.  Black is up the exchange, but white has an advanced passed pawn and his knight and king are more active than black's pieces.  Black is playing for a win and has the simple plan of trading his rook for white's knight and a pawn, while white is playing for a draw and has reasonable drawing chances.  White's immediate threat is to capture black's rook with Kxc5  He has no other threats.  Let's look at the five defensive ideas to see what candidate moves we find, and then pick the best move.

Idea 1 (capture, pin, deflect):  none.
Idea 2 (block):  none.
Idea 3 (move):  the rook has nine legal moves several of which are clearly unsafe, but a few look interesting: Rxf5, Rc6, Rc7, and Rc8.
Idea 4 (defend):  black cannot add a defender to the rook.
Idea 5 (counterattack with an equal or greater threat to WIN, DRAW, DEFEND):  an equal threat would be to attack a rook or to return some his material for some other concrete advantage, but neither idea is possible here.  A greater threat would be to attack the king, but neither check is safe for black.

This was probably the easiest list of candidate moves to find so far!  So let's start with the most forcing reply first: 1...Rxf5:

Black has now won a pawn and has connected passed pawn on the kingside and will certainly win...that is, unless white can find a refutation.  This position is now the kind of thing you'd see in Bain's tactics book, and would make a wonderful tactical puzzle for beginners.  What kind of thought process could help beginners find white's refutation?  Well, first of all the right approach is just asking yourself -- before you touch the rook -- "is 1...Rxf5 safe?"  You should ask that question every single time you are about to make a move, especially a move that doesn't create a specific threat.  Certain visual patterns give you ideas to help find offensive moves (the topic of yet another future blog series), and in this position hopefully everyone can see the knight fork 2. Ne7+ which refutes black's move.  There are three visual clues that could lead one to immediately find the fork:  the proximity of the knight to the black's pieces, the specific colors (knights fork targets that are on the color they are currently standing on), or the specific geometry of the location of the targets (in this case one square away on a file/rank, or on the adjacent diagonal squares).

So even though our four candidate moves were rather simple to find, the thought process of searching for your opponent's most forcing reply should be engrained in all beginners.  That one single question alone, plus lots of tactical training, should allow you to find white's refutation and hopefully avoid making complete blunders.  Here again I would make the same point I have made before...if you stop and look for refutations but miss certain patterns, you should go train those patterns until you don't miss them anymore.  But the key is to ask the question.

We can very quickly see that of black's four candidate moves, only one of them (1...Rc7) avoids the knight fork.  After doing the same satefy check as above, you can see that the rook is totally safe on c7, and the game continues...