Friday, February 13, 2015

Calculating Forcing Moves: Defensive Idea 1, Part 3 (Deflect the Attacker)

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 two different ways to implement the first defensive idea:  capture the attacking piece, and pinning the attacking piece.  This post will explore the third and final way to implement the first idea (of doing something to the attacking piece) by looking at deflection.

The basic idea here is to get the attacking piece to go do something more important than what it is currently threatening.  I think this idea might be more of a counterattack and could be better placed in Idea 5 than Idea 1.  The two questions that come to mind are: (1) are there any positions where deflection can be achieved without creating a greater threat (counterattacking)?; and, (2) how are the counterattacking goals in Idea 5 different?  Perhaps deflection is a sort of a hybrid of 1 and 5.  I'm not quite sure yet.

The general process is to evaluate the position, identify 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.

Black just played Na7 discovering an attack against the White queen.  White to move.

2rr3k/n2p1R2/1pb5/p5pN/Q1Pp3p/PP6/6PK/8 w - - 0 1

Let's first evaluate the position, and then identify black's threats.  Each side has a rook and a knight, white has four pawns to black's six, so the material balance is a queen vs rook, bishop and two pawns.  Black is up one point, but the black king is weak and white's rook and knight are active.  Black has a passed pawn but that seems irrelevant at the moment (the white king can step into its square with Kg1 if needed).  Black's threat is to capture the queen on a4 and then the c4 pawn (1. (skip) Bxa4 2. bxa4 Rxc4), which would leave black ahead a rook a three pawns which is winning .  Let's see if any of the five defensive ideas allow white to keep his queen.

Idea 1 (capture, pin, deflect):  white can capture the bishop (Qxc6).  White cannot pin the bishop to something of equal or greater value.  To find the deflection in this particular position (and perhaps in all cases?) we need to look at counterattacking options, which we'll do below in Idea 5.
Idea 2 (block):  none
Idea 3 (move):  The queen has three moves (Qxa6, Qb5, Qb4) all of which appear to fail, but we might return to these moves out of desperation if other candidates don't save the queen.
Idea 4 (defend):  White cannot add another defender to the queen.
Idea 5 (counterattack with an equal or greater threat to WIN, DRAW, DEFEND):  an equal threat would be to attack black's queen which isn't an option here.  A greater threat would be to attack the king, gaining a tempo to either with the game, force a draw, or use one of the other defensive ideas.  White has two checks (Rh7+ and Rf8+) both of which seem to fail. White can create a mate in 1 threat with 1. Nf6 (an Arabian Mate pattern).

That gives us seven candidate moves to calculate (Qxc6, Qxa6, Qb5, Qb4, Rh7+, Rf8+, and Nf6).  Where to start?  With the most forcing, of course.  The most forcing replies are the mate threat and capturing the bishop (in that order), so let's start with 1. Nf6:

What is white's threat?  After 1. Nf6 (skip) 2. Rh7#  I do not see any other threats for white.  So now black needs to find a defense to white's mate in 1 threat.  Let's look at the five ideas now for black:

Idea 1: Black cannot capture the rook or knight, and cannot pin the rook to the white king.  No deflections.
Idea 2: No blocks.
Idea 3: The black king is stalemated, and cannot move or create an escape square.
Idea 4: Black can defend the mating square on h7 by playing 1...Be4.
Idea 5: Black has no checks, so no counterattacking possibilities.

Black has ONLY one defensive candidate move, so after 1. Nf6 Be4:

Black now has zero threats that I can see.  Therefore white is free to play any move he wants, keeping in mind he is down one point.  Now 2. Rh7+ fails because h7 is defended twice, so let's look at the obvious capture and see if black has any refutations, so after 1. Nf6 Be4 2. Nxe4:

White is now up two points, and has the threat to return his knight to f6 again threatening mate on h7, which gives black two tempos to defend.  Black has zero checks, and zero captures (Rxc4 looks pretty bad).  He could simply attack the rook with 2...Kg8 which also addresses the mate threat, but white simply has too many options, and at this point I would be comfortable as white saying 1. Nf6 is safe.  It saves the queen AND puts white ahead materially (by two points).  This is our KOTH candidate move.

The only other move worth considering is simply capturing the bishop so that white can try the Arabian mate again.  So let's see if black can stop the mate after at 1. Qxc6:

White is now ahead materially, and has three threats: capture a pawn (2. Qxb6), a mate in 2 by force (2. Qh6+/Qh7#), and Arabian mate in 2 (2. Nf6/Rh7#).  Black can restore his material lead and address all three threats with 1...Rxc6, defending the f6 square, and leaving black ahead an entire rook.  If white continues with 2. Nf6, black can simply capture with 2...Rxf6 3. Rxf6 Nc6 (blocking to protect the b6 pawn), after which white has no threats and black is now ahead a knight and two pawns, which is winning.  That means our KOTH is still 1. Nf6 Be4 2. Nxe4.

The search strategy of looking for counterattacks (from the Idea 5 basket) is what allowed us to find the mate-in-1 threat which forced white to divert the attacking piece (bishop) away from the queen.  However, since the end-result was in the Idea 1 basket of "somehow dealing with the attacking piece", I'm going to leave this idea in Idea 1 for now.  After looking more deeply at counterattacking positions I might come back to this, but for now my sense is that while the search strategy is from Idea 5, the end-state is Idea 1.

But what is more important, categorizing by search strategy or end-states?  Hmm...


  1. "Now 2. Rh8+ fails because h8 is defended twice, so let's look at the obvious capture"

    "...a mate in 2 by force (2. Qh6+/Qh7#), and Arabian mate in 2 (2. Nf6/Rh8#)".

    As far as I can checked it out - you probably meant Rh7+ and Rh7# respectively.

    And Idea 5 is the broaedest sense of defending, however Idea 1 is a specific sub-group of "how to execute the Idea 5". I am not sure if you catch what I mean, but in this case a form of a counterattack (Idea 5) is based on Idea 1. At least this is how I see it now.

    1. Tomasz -- thanks, you're right! I fixed those to h7 instead of h8.

      Idea 5 is indeed the broadest, but it is also the most aggressive because essentially you are ignoring the threat against you by creating a stronger (or equal) threat that your opponent has to deal with.

      Like Idea 1 which has three subgroups, Idea 5 also has three subgroups: counterattack to win, to draw, or to defend. The idea 5 method 1 is counterattacking to win, and means completely ignoring the threat against you to create an equal or greater threat of your own. The goal of Idea 5 method 2 is to force a draw by repetition or stalemate. The goal of Idea 5 method 3 is to use a tempo (by creating a greater threat) to allow another defensive idea to play out, one of which is capturing the attacker...not forcing the attacker to capture you.

      So in that way deflection is sort of a hybrid of Idea 1-3 and Idea 5-3, instead of a subset of either one. But I go back to my original two questions -- (1) can you force a deflection without creating a greater threat (I'm searching for positions to prove it either way), and (2) what is goal of the categories in these ideas? Is it either the search strategy involved to find candidate moves, or is it the end-state? I think the search strategy is more important, but I'm not sure yet.

  2. It is a great pleasure to read your posts. Despite it they are very inspirational as the examples are very well chosen and the explanation is amazing :). These classifications are too difficult to me, but I appreciate your lecture very much! Keep up great work and I will try to search for any mistakes or explanation not clearly laid out. I hope it helps you to create great context! :)

    1. Oh, no!! The classifications shouldn't be hard to understand. Perhaps I need to do a better job of explaining the idea?? What part of it doesn't make sense?

  3. I mean the WHOLE classification - I would be extremally glad and grateful if you would provide some kind of the table. This way I would be able to see what are the connections between them and which concepts are sub-group of another ones.

    You can look at my blog post to see what I mean (these are shown the methods of defence against check). And of course the more examples and explanations you will provide, the better I would be able to understand the whole concept you want to share.

    Here is the link:

  4. Ok, I'll make a table showing the ideas. There's really no point giving these examples if the core idea isn't clear!!