Calculation: long lines is lesson 1 of 9 in Real-game tactics 7: Calculation and defence, a tactics course suited to players rated around 1800 (strong club players). Forcing sequences of four moves or more. Picture the board after every move. It has 7 interactive exercises: 7 calculated lines from real positions. You play every move on a board and get feedback straight away. The lesson is free.
What you practise
Black to move and win.
Black to move: mate in 4. (5 positions)
White to move and win.
Worked examples
Black to move and win. 1...Ne4+ 2.Kd3 Qxg2 3.Bxg2 Nf2+ 4.Kd2 Nxd1. The queen sacrifice on g2 dragged the bishop away from its duty. You come out 5 points ahead in material.
Black to move: mate in 4. 1...Bg3+ 2.Bh3 Qxh3+ 3.Kg1 Qh2+ 4.Kf1 Qf2#. Moving the bishop opened the line for the queen on h5. Mate in 4.
More in Real-game tactics 7: Calculation and defence
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