Search results for " Computer Science"
showing 10 items of 3983 documents
On the number of factors of Sturmian words
1991
Abstract We prove that for m ⩾1, card( A m ) = 1+∑ m i =1 ( m − i +1) ϕ ( i ) where A m is the set of factors of length m of all the Sturmian words and ϕ is the Euler function. This result was conjectured by Dulucq and Gouyou-Beauchamps (1987) who proved that this result implies that the language (∪ m ⩾0 A m ) c is inherently ambiguous. We also give a combinatorial version of the Riemann hypothesis.
Heuristics for the bi-objective path dissimilarity problem
2009
In this paper the path dissimilarity problem is considered. The problem has previously been studied within several contexts, the most popular of which is motivated by the need to select transportation routes for hazardous materials. The aim of this paper is to formally introduce the problem as a bi-objective optimization problem, in which a single solution consists of a set of p different paths, and two conflicting objectives arise, on one hand the average length of the paths must be kept low, and on the other hand the dissimilarity among the paths in the set should be kept high. Previous methods are reviewed and adapted to this bi-objective problem, thus we can compare the methods using th…
Comparing multicriteria methods in the context of environmental problems
1998
Abstract The present paper gives an analysis of the use of ELECTRE III, PROMETHEE I, II, and SMART decision-aids in the context of four different real applications to environmental problems in Finland. These methods are widely used decision-aids in the real planning processes. The purpose of this study is to define the differences of these methods and the results obtained with them, and in this way also to consider their applicability in aiding environmental decision-making. Furthermore, a comparison of the methods based on a set of randomly generated problems is carried out. The choice in practice will not be easy; PROMETHEE does not differ much from SMART with linear value functions, and …
A multiple layered functional data model to support multiple representations and interoperability of GIS
2001
This paper presents a multi-layered functional data model to support multiple representation and information sharing among distributed spatial information systems. The key idea is that a geographical space (foe example an urban space) can be viewed as a set of abstract spatial functionalities on which different application classes can be derived to manipulate objects of the same geographical space and share the same abstract generic functionalities. The object classes define multiple views or representations of a domain. For example in urban management, transportation systems, water supply and sewage systems applications can share generic network functionalities defined by graph treversal o…
A Novel Multidimensional Scaling Technique for Mapping Word-Of-Mouth Discussions
2009
The techniques which utilize Multidimensional Scaling (MDS) as a fundamental statistical tool have been well developed since the late 1970’s. In this paper we show how anMDS scheme can be enhanced by incorporating into it a Stochastic Point Location (SPL) strategy (one which optimizes the former’s gradient descent learning phase) and a new Stress function. The enhanced method, referred to as MDS SPL, has been used in conjunction with a combination of the TF-IDF and Cosine Similarities on a very noisy Word-Of-Mouth (WoM) discussion set consisting of postings concerning mobile phones, yielding extremely satisfying results.
A Logical Explication of the Concepts of Incomplete and Uncertain Information
1994
Discovery of elementary knowledge and its constituents, i.e. information contained in objects of reality is realized through asking questions including certain aspects called attributes in this paper. We describe a fragment of a discovered reality as an information system (cf. Pawlak [1,3,4]), which consists of the universum U of all the objects of this reality we are concerned with, and of a set A of attributes understood as functions each of which assigns to every object of U 1) a value of given attribute belonging to A or 2) an interval of approximate values of this attribute, i.e. an established set of possible values of this attribute. From the point of view of the cognitive agent and …
Scatter Search and Path-Relinking: Fundamentals, Advances, and Applications
2010
Scatter search is an evolutionary metaheuristic that explores solution spaces by evolving a set of reference points, operating on a small set of solutions while making only limited use of randomization. We give a comprehensive description of the elements and methods that make up its template, including the most recent elements incorporated in successful applications in both global and combinatorial optimization. Path-relinking is an intensification strategy to explore trajectories connecting elite solutions obtained by heuristic methods such as scatter search, tabu search, and GRASP. We describe its mechanics, implementation issues, randomization, the use of pools of high-quality solutions …
Fundamentals of a Generalized Measure Theory
1999
In this chapter, we try to present a coherent survey on some recent attempts in building a theory of generalized measures. Our main goal is to emphasize a minimal set of axioms both for the measures and their domains, and still to be able to prove significant results. Therefore we start with fairly general structures and enrich them with additional properties only if necessary.
Checking the Efficacy of Two Basic Descriptors With a Set of Properties of Alkanes
2019
Several experimental properties of alkanes are described by means of multilinear models at the cross-validation level. The models have been obtained considering two main sets of descriptors: mathematically-based and experimental ones. The best models are obtained normally involving one of the two sets. The main goal of this work is to show how the theoretical descriptors are able to perform a competitive role against the experimental ones. This constitutes an important topic in the quantitative structure-property relationships field because the use of mathematical and in silico descriptors is validated as a proper tool for model building. Activity distributions of the properties and indices…
An Introduction to Computational Complexity
2016
This chapter is not strictly about algebra. However, this chapter offers a set of mathematical and computational instruments that will allow us to introduce several concepts in the following chapters. Moreover, the contents of this chapter are related to algebra as they are ancillary concepts that help (and in some cases allow) the understanding of algebra.