SFI WORKING PAPER: 2010-11-027 SFI Working Papers contain accounts of scientific work of the author(s) and do not necessarily represent the views of the Santa Fe Institute. We accept papers intended for publication in peer-reviewed journals or proceedings volumes, but not papers that have already appeared in print. Except for papers by our external faculty, papers must be based on work done at ...

In this paper we consider the problem of enumerating the submultisets of a multiset, in which each element has equal multiplicity. The crucial property is that consecutive submultisets in this listing differ one in the cardinality of only one of the elements. This is a generalization to k-ary numbers of the so-called Gray Codes for binary numbers. In the special case of binary numbers there is ...

We propose a new procedure that can enumerate justifications of a logical entailment given a set of inferences using which this entailment can be derived from axioms in the ontology. The procedure is based on the extension of the resolution method with so-called answer literals. In comparison to other (SAT-based) methods for enumerating justifications, our procedure can enumerate justifications...

It is known experimentally that there is a threshold for satisfiability in 3-CNF formulre around the value 4.25 for the ratio of variables to clauses. It is also known that the threshold is sharp [Fri99], but that proof does not give a value for the threshold. We use purely combinatorial techniques to count the number of satisfiable boolean formulre given in conjunctive normal form. The intenti...

Packing problems, which ask how to arrange a collection of objects in space to meet certain criteria, are important in a great many physical and biological systems, where geometrical arrangements at small scales control behavior at larger ones. In many systems there is no single, optimal packing that dominates, but rather one must understand the entire set of possible packings. As a step in thi...

Metaquerying is a data mining technique by which hidden dependencies among several database relations can be discovered in the form of Datalog-like rules, and this technique has already been successfully applied to several realworld application domains. Unfortunately, recent papers have shown that performing metaquerying turns out to be in general quite demanding from the computational viewpoin...