Thursday, August 30, 2012

Black unpins White

Arnoldo Ellerman (12.01.1893-21.11.1969), an Argentine, was a prolific composer of two-movers. He showed many Black line-themes (interference and shut-offs) in the Good Companion problem folders. Here, the theme is Black unpinning White, not out of kindness, but to avert a threat. This will cause another defect in the Black position, allowing precisely separated mates.

1. Qh1! [ Threat >2. Qf3#]

1. ... Rd4 Interference with dark sq bishop allowing 2. Sf6#

1. ... Rc3 Interference with dark sq bishop allowing 2. Sf6#

1. ... Rd3 Interference unpin of white rook 2.Shut-off (of Rd3), discovered mate 2.Re3#

1. ... Bxe2+ 2. Bxe2# is not thematic

1. ... Rc4 Interference unpin of white rook 2.Shut-off (of Rc4), discovered mate 2.Re4#

1...Bb7 Withdrawal unpin of white rook 2.Shut-off (of Bb7), discovered mate 2.Re4#

1. ... Bc8 Withdrawal unpin of white rook 2.Shut-off (of Bc8), discovered mate 2. Re6#

1. ... Kg4 (a flight granted by key) 2. Qf3#

The beauty of the problem is the combination of the two ways in which a line-piece may be unpinned, by interference and by withdrawal. It will pay for newcomers to play over these beautiful variations.

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