On Correctness and Completeness of an n Queens Program

Thom Fr\"uhwirth presented a short, elegant and efficient Prolog program for the n queens problem. However may be seen as rather tricky one not convinced about its correctness. This paper explains in declarative way, provides proofs of correctness completeness. The specification are declarative, i.e. they abstract from any operational semantics. is approximate, it unnecessary to describe program's semantics exactly. Despite works on non-ground terms, this work employs standard semantics, based logical consequence Herbrand interpretations. Another purpose present an example precise reasoning logic program. Under consideration Theory Practice Logic Programming (TPLP).