Babson task

A Babson task (or simply Babson) is a <a href="/facts/Glossary_of_chess_problems/UgYUfjxg">directmate</a> <a href="/facts/Chess_problem/jVyYlAXs">chess problem</a> with the following properties:

<ol><li>White has only one <a href="/facts/Glossary_of_chess_problems/UgYUfjxg">key</a>, or first move, that forces <a href="/facts/Checkmate/0TrSapPq">checkmate</a> in the stipulated number of moves.</li>
<li>Black's defences include the <a href="/facts/Promotion_(chess)/V1rtTYu2">promotion</a> of a certain <a href="/facts/Pawn_(chess)/Xk3E1UIN">pawn</a> to a <a href="/facts/Queen_(chess)/sHWc1RMX">queen</a>, <a href="/facts/Rook_(chess)/Douvk8Nu">rook</a>, <a href="/facts/Bishop_(chess)/d1jHm7Ec">bishop</a>, or <a href="/facts/Knight_(chess)/zhuevLvX">knight</a>. (Black may have other defences as well.)</li>
<li>If Black promotes, then the only way for White towards a forced checkmate in the stipulated number of moves is to promote a pawn to the same piece to which Black promoted.</li></ol>
Joseph Ney Babson [it] (1852–1929), the task's eponym, first conceived of the task in 1884, but never solved it.
To devise a satisfying Babson task is regarded as one of the greatest challenges in <a href="/facts/Chess_composer/8ynqUbjX">chess composing</a>. For almost a century, it was unknown whether such a task could exist.
The Babson task is a special form of <a href="/facts/Allumwandlung/Urs6GSjP">Allumwandlung</a>, a chess problem in which the solution contains promotions to each of the four possible pieces. Such problems were already known when Babson formulated his task.

Babson task open-in-new

Babson task