Abstract
The n-queens problem is to place n queens (where n > 0) on an n -by-n chessboard so that no queen is threatened by another one. According to the rules of chess, this is equivalent to the requirement that no two queens be on the same row or the same column or on a common diagonal. For some values of n this is possible but for some values (for example, for n =2) there is no solution. In this chapter we show how one solution for a particular value of n is found with a depth-first search. The program derivation illustrates both recursion and loop introduction in a nontrivial setting. It also illustrates how to handle data structures like sequences in a program derivation.
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© 1998 Springer Science+Business Media New York
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Back, RJ., von Wright, J. (1998). The N-Queens Problem. In: Refinement Calculus. Graduate Texts in Computer Science. Springer, New York, NY. https://doi.org/10.1007/978-1-4612-1674-2_24
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DOI: https://doi.org/10.1007/978-1-4612-1674-2_24
Publisher Name: Springer, New York, NY
Print ISBN: 978-0-387-98417-9
Online ISBN: 978-1-4612-1674-2
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