notyetagm: Position after 21 h2-h4!?
click for larger viewHere White (Shirov) has just played 21 h2-h4!?, setting up an interesting trap. What happens if Black simply grabs the White h4-pawn with his Black g5-pawn? (VAR) Position after 21 ... g5xh4??
click for larger viewBy playing the blunder 21 ... g5xh4??, Black has opened the diagonal c1-h6 to his <UNDEFENDED> Black h6-rook. Before opening this diagonal, the <UNDEFENED> Black h6-rook was not really a weakness because it could not be attacked (exploited). After 21 ... g5xh4?? it can be exploited because it can be attacked along the newly opened c1-h6 diagonal, so now it really -is- a weakness. Black has a second weakness, the Black a5-queen which is almost <TRAPPED ON THE EDGE OF THE BOARD> and would in fact be <TRAPPED> if White could play his dark-squared White d4-bishop to b6. So how does White exploit these <TWO WEAKNESSES>, the <UNDEFENDED> Black h6-rook and the almost <TRAPPED> Black a5-queen? With the <QUEEN FORK> 22  e2-e3!. (VAR) Position after 21 ... g5xh4?? 22 e2-e3! <queen fork> 
click for larger view22 e2-e3! is a <DOUBLE ATTACK> against the <UNDEFENDED> Black h6-rook and the b6-trapping square. White threatens both 23 e3x h6 and 23  d4-b6 <TRAPPING> the Black a5-queen, winning material. In the vocabulary of Weteschnik, 22 e2-e3! is a <DOUBKE ATTACK> in which the <TACTICAL BASE> is the e3-square, one <TACTICAL TARGET> is a piece (<UNDEFENDED> Black h6-rook), and the other <TACTICAL TARGET> is a square (b6-trapping square). <WETESCHNIK>: -EVERY- square (b6-trapping square) which can be reached from the <TACTICAL BASE> (e3-square) must be considered as a potential second <TACTICAL TARGET>. The e3-square became a <TACTICAL BASE> when Black played 21 ... g5xh4?? and made it possible for the White e2-queen to attack the <UNDEFENDED> Black h6-rook. | 
