## The N-Queens Problem

- in the language of lparse (Version 1.0.13):
queens
- in the language of ccalc (Version 1.9):
queens.b

The formulation of the N-queens problem in the language of ccalc above
is *absolutely tight*
in the sense of
"Tight logic programs," by E. Erdem and
V. Lifschitz (in TPLP, Vol. 3, pp. 499-518, 2003.)

The formulation of the N-queens problem in the language of ccalc, with
nested expressions, is
equivalent to its formulation in the language of lparse, with cardinality
constraints. This is due to equivalent transformations of
"Weight
constraints as nested expressions," by P. Ferraris and V. Lifschitz
(to appear in TPLP).

The performances of smodels and ccalc on this problem, in terms of
computation time, is discussed in [Erdem & Lifschitz, 2003] mentioned
above.
A comparison of smodels and cmodels on this problem is
presented in the
note comparison.ps
prepared by Y. Lierler.