Lessons column by Eddie Williams

PARITY

Game 1: at move 58, white has two out of the three empty squares to choose from.  White has no access to g7, and is looking at having to pass, and give the last move to black.  With f1, black has to go e1, and then the final g7 belongs to black.  Counting stones for white, it adds up to 31+ (f1= +5, e1= -2, g7= -3 =0) =31 final for white.  E1 looks like a worse choice on the surface, because it takes 7 but then loses 8 to black's f1!  However, this changes everything for white, because since f6 is now black, g7 is available!  and g7's +2 count makes it a 32-32 result.  This is an excellent example of how getting the last move can be such an advantage, and also demonstrates the importance of counting stones. (show board at move 58, maybe one after 59.e1).

Game 2: after move 42.b2, white begins to establish parity in each section of the board.  Black has little mobility now and has to attempt to wedge at g8 should white take h8.  White's a2 creates the parity section on the north, if black takes a1, white goes e1.  After 47.b7, 48. a5 establishes two more parity sections, a4/b4 and a7/a8.  If black moves in one, white has the easy response.  Finally, black's only move is a1, to which white takes e1.  After 55.g2, white has parity in the both remaining corners, since white can take both h8 and g8.  This shows how parity is a vital factor in forcing an opponent's moves. (show boards at 42.b2, and 48.a5) b2 h7 h4 g7 a2 b7a5 b4 a5 a1 e1 a7 a8 g2 h1 g1 h2 h8 g8

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