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).

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