12232435
Rational Transformations of Formal Power Series
Formal power series are an extension of formal languages. Recognizable formal power series can be captured by the so-called weighted finite automata, generalizing finite state machines. In this paper, motivated by codings of formal languages, we introduce and investigate two types of transformations for formal power series. We characterize when these transformations preserve rationality, generalizing the recent results of Zhang [15] to the formal power series setting. We show, for example, that the "square-root" operation, while preserving regularity for formal languages, preserves rationality for formal power series when the underlying semiring is commutative or locally finite, but not in general.
27034466
Power Defaults
We present a spectrum of default logics, using powerdomains to encode default constraints. The resulting nonmonotonic entailment relations all satisfy the law of reasoning by cases. This result is a consequence of two general theorems valid for any Scott domain: the Dichotomy Theorem and the Extension Splitting Theorem. We briefly indicate that for propositional logic, the complexity of entailment is complete for co-NP(3).
17607240
Reasoning with power defaults
This paper introduces power default reasoning (PDR), a framework for non-monotonic reasoning based on the domain-theoretic idea of modeling default rules with partial-information in a higher-order setting. PDR lifts a non-monotonic operator at the base (syntactic) level to a well-behaved, almost monotonic operator in the higher-order space of the Smyth power-domain --effectively a space of sets of models. Working in the model space allows us to prove the dichotomy theorem and the extension splitting theorem, leading to a more well-behaved logic and (modulo the usual complexity conjectures) a less complex logic than standard default logic. Specifically, we prove that skeptical normal default inference is a problem complete for co-NP(3) in the Boolean hierarchy for strict propositional logic and NP(4)-complete in general. These results (by changing the underlying semantics) contrasts favorably with similar results of Gottlob (J. Logic Comput. 2(3) (1992) 397-425), who proves that standard skeptical default reasoning is Π2P-complete. Furthermore, we show that the skeptical non-monotonic consequence relation, defined using our domain-theoretic semantics, obeys all of the laws for preferential consequence relations defined by Kraus, Lehmann, and Magidor. In particular, we get the property of being able to reason by cases, and the so-called law of cautious monotony. Both of these laws fail for the standard propositional default logic of Reiter (Artificial Intelligence 13 (1980) 81-132), but hold in PDR as a consequence of the dichotomy theorem and the extension splitting theorem.
15029835
Quasi-Prime Algebraic Domains
Abstract The purpose of this paper is to introduce a new class of domains called quasi-prime algebraic domains. We show that this class is a good candidate for the purpose of denotational semantics of programming languages. This is achieved by exhibiting many constructions usually needed for denotational semantics on quasi-prime algebraic domains. In the first part we motivate the notion of quasi-primes and quasi-prime algebraic domains by studying the effect of linear functions on domains that are not prime algebraic. In the second part we study categories of quasi-prime algebraic domains by representing them as irreducible information systems. We introduce a symmetric monoidal closed category of quasi-prime algebraic domains with quasi-linear functions. We show further that with the usual Scott continuous functions as morphisms, quasi-prime algebraic domains are cartesian closed. In the third part we show the existence of a saturated quasi-prime algebraic domain, and introduce a framework for solving domain equations in quasi-prime algebraic domains. It is then possible to give, for example, a model for the un-typed lambda calculus with a reflexive quasi-prime algebraic domain.
205118584
dI-Domains as Prime Information Systems
Abstract This paper introduces prime information systems. Prime information systems determine dI-domains and stable approximable mappings give stable functions, and vice versa. The notion of rigid embedding is captured by a subsystem relation. Under this relation, prime information systems form a complete partial order (cpo). Constructions like lifting, sum, product, and function space are proposed which induce continuous functions on the cpo. In this way recursive prime information systems can be defined using fixed point theory.
1726106
Defaults in Domain Theory
Abstract This paper uses ideas from artificial intelligence to show how default notions can be defined over Scott domains. We combine these ideas with ideas arising in domain theory to shed some light on the properties of nonmonotonicity in a general model-theoretic setting. We consider in particular a notion of default nonmonotonic entailment between prime open sets in the Scott topology of a domain. We investigate in what ways this notion obeys the so-called laws of cautious monotony and cautious cut , proposed by Gabbay, Kraus, Lehmann, and Magidor. Our notion of nonmonotonic entailment does not necessarily satisfy cautious monotony, but does satisfy cautious cut. In fact, we show that any reasonable notion of nonmonotonic entailment on prime opens over a Scott domain, satisfying in particular the law of cautious cut, can be concretely represented using our notion of default entailment. We also give a variety of sufficient conditions for defaults to induce cumulative entailments, those satisfying cautious monotony. In particular, we show that defaults with unique extensions are a representation of cumulative nonmonotonic entailment. Furthermore, a simple characterization is given for those default sets which determine unique extensions in coherent domains. Finally, a characterization is given for Scott domains in which default entailment must be cumulative. This is the class of daisy domains ; it is shown to be cartesian closed, a purely domain-theoretic result.
37771428
Some New Bounds on Single-Change Covering Designs
A single-change covering design SCD(v, k, b) on a c-set V is a sequence of b k-sets (blocks) on V that together cover every pair of elements of V at least once, such that two successive blocks have k-1 elements in common. Let f(v,k) denote the smallest b for which there exists an SCD(v, k, b). Some new upper and lower bounds for f(v,k) are given.
41994930
On the partition and coloring of a graph by cliques
Abstract We first introduce the concept of the k -chromatic index of a graph, and then discuss some of its properties. A characterization of the clique partition number of the graph G ⋁ K c m for any simple graph G is given, together with some of its applications. Graphs with maximum valency 3 are also considered.
30701744
Single change covering designs
A single-change covering designSC (v, k, b) on av-setV is a sequence ofb k-sets (blocks) onV which together cover every pair of elements ofV at least once, such that two successive blocks havek−1 elements in common. It is desirable to minimizeb. Some constructions and lower bounds forb are given.
42909091
Combining path relinking and genetic algorithms for the multiple-level warehouse layout problem
Path relinking is a method to generate new solution by exploring trajectories that connect high quality solutions. In this paper, a class of new hybrid heuristics are proposed by combining a genetic algorithm and path relinking and applying these to a multiple-level warehouse layout problem. Parallel and series combinations to integrate crossover and mutation operations of a genetic algorithm with path relinking are investigated. We proposed position and sequence based path relinking methods to connect two solutions, which are either elites or ones selected randomly. Extensive experiments are carried out to compare the performance of the new heuristics.
38503566
Pseudo-one-factorizations of regular graphs of odd order - II. products of graphs
Abstract We study the pseudo-one-factorization of regular graphs of odd order. It is shown that some classes of products (including composition and cartesian product) of graphs are pseudo-one- factorizable. In particular, we prove that a complete regular t -partite graph of odd order has this property.