09-20

The Berlin theme doubled: once realized, once preventively avoided

Berlin theme (New German Logic): a mainplan by White forces Black to mate him as Black’s unique defense. After a foreplan, the mating move is downgraded to a mere check.



Try (main plan): 1.Rdd8? (thr. 2.Rac8#) Kc6!

Try:1.b5 (thr. 2.b6#) axb5 2.Rdd8? Ra1#! Berlin-mate-1

Try:1.Be3 (thr. 2.Bb6#) Rxe3 2.b5 axb5 3.Rdd8? Ra1#! Berlin-mate-2

Solution:

Foreplan-1: 1.Bg2 (thr. 2.Rdd8 3.Rac8) Rxg2 (Berlin-mate-2 preventively avoided)

Foreplan-2: 2.Be3 Rxe3 (Roman decoy)

Foreplan-3: 3.b5 axb5

Main plan: 4.Rdd8 Ra3+ (Berlin-mate-1 downgraded) 5.bxa3 Kc6 6.Rac8#