Chessville - Chessprints - For the sheer JOY of chess! - Chess Positions from chess games, chess compositions, chess studies, etc.

Chessville
...by Chessplayers, for Chessplayers!

Today is

Site Map

If you have disabled Java for your browser, use the Site Map (linked in the header and footer).

Chessville
logo by
ChessPrints

Advertise
with
Chessville!!

Advertise to
thousands
of chess
fans for
as little
as $25.

Single insert:
$35
x4 insert:
@ $25 each.

From the
Chessville
Chess Store

Chessprint
May 18, 2008

A twin refers to multiple settings of a problem, which differ from one another slightly in their positions, but each requiring its own solution. The problem below has a twin by moving the black king from f5 to h5.

[FEN 7n/6r1/3n1pNp/3K1k2/3B4/8/6Q1/8 w - - 0 1]
[FEN 7n/6r1/3n1pNp/3K3k/3B4/8/6Q1/8 w - - 0 1]

White Mates in 2 [(b) Kf5 to h5]

Solution

[Index of Chessprints]

Chess Books & Supplies

Solution

Another great problem from
Peter's Problem World

A twin refers to multiple settings of a problem, which differ from one another slightly in their positions, but each requiring its own solution. The settings are produced by making small adjustments to the initial diagram. Problem 10 demonstrates such a twin with two parts. The diagram position is regarded as part (a), which solves normally. The stipulation then specifies that part (b) be formed by shifting the black king to h5, and this position is to be solved anew. Besides shifting a piece to another square, other methods of twinning are possible, such as adding or removing a piece, and replacing one piece with another.

10. Josef Retter
Hashavit Memorial Tourney 1982, 3rd Prize

Part (a) of this problem starts with 1.Be3!, which threatens 2.Nh4. Black has only two defences, both self-blocks that provoke queen mates, 1…Rxg6 2.Qf3, and 1…Nxg6 2.Qh3.

Part (b) has the key 1.Bxf6!, threatening 2.Nf4. The same defences by Black are playable, but they lead to a special type of changed play called reciprocal change. In this scheme, two White mating moves that work against two defences respectively in one phase are effective again in another phase, but these mates have to be swapped in dealing with the two defences, so here 1…Rxg6 2.Qh3, and 1…Nxg6 2.Qf3.