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Knuth: reversible list operations for exact-cover search

Knuth presented dancing links as an implementation technique for backtracking, using reversible deletion and restoration of nodes in doubly linked lists and applying it to Algorithm X for exact cover.

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Knuth presented dancing links as an implementation technique for backtracking, using reversible deletion and restoration of nodes in doubly linked lists and applying it to Algorithm X for exact cover. During a tentative choice, incompatible rows and columns can be removed and then restored cheaply when the search backtracks. The data structure makes changing constraints manageable while leaving the underlying combinatorial search problem intact.

Source-linked catalogue note. A detailed explanatory guide has not yet been prepared for this entry.

Scientific scope

This is a search implementation technique, not a polynomial-time algorithm for general exact cover. The opening credits Hitotumatu and Noshita's earlier use of reversible list operations.

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Donald E. Knuth

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English catalogue narrative

Knuth: reversible list operations for exact-cover search

Knuth presented dancing links as an implementation technique for backtracking, using reversible deletion and restoration of nodes in doubly linked lists and applying it to Algorithm X for exact cover.

During a tentative choice, incompatible rows and columns can be removed and then restored cheaply when the search backtracks. The data structure makes changing constraints manageable while leaving the underlying combinatorial search problem intact.

Scientific scope

This is a search implementation technique, not a polynomial-time algorithm for general exact cover. The opening credits Hitotumatu and Noshita's earlier use of reversible list operations.

People and systems

Donald E. Knuth

Original sources