14 April 2013

Annotated Game #90: R+P <> N+B

This fourth-round tournament game offers some interesting lessons and contrasts in how to count the material balance.  I did well out of the opening as Black, then faced a major decision on move 10, whether or not to take the f2-pawn.  Houdini validates the choice made in the game, which focuses instead on not falling too far behind in development.  However, several moves later, Black again targets the f-pawn and does the classic B+N for R+P exchange.  This is a classic material counting error, from the days where a piece was considered to be worth 3 pawns.  In reality, it's better to consider a piece as 3.25 pawns, which makes it clear that the above trade is detrimental.  The bishop pair can also be considered to be worth up to 0.5 pawns as a rule of thumb, making the trade even worse on counting considerations alone.

I wasn't completely ignorant of the above at the time, but also made an error in judgment in this particular game that the rooks would be able to compensate by operating down the central files.  This turned out not to be the case, as by move 22 it's clear that the rooks have nowhere to go and cannot penetrate - until White blunders by snatching a pawn and allowing a rook fork on the second rank.

As a secondary lesson, this game pointed out a consistent thought process error, which was Black's failure to advance the g-pawn (on two different occasions) to attack and trap the White knight.  Black simply failed to even consider the possibility of a g-pawn advance, based on the "general principles" of not making weakening pawn moves in front of the king.  This is another example of where using CCT (Checks, Captures and Threats) would have resulted in finding the correct candidate move (the threat to trap the knight), which was worth far more than the resulting positional weakness.

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