Generalization of Pattern-growth Methods for Sequential Pattern Mining with Gap Constraints

Abstract The problem of sequential pattern mining is one of the several issues that have deserved particular attention on the general problem of data mining. Despite the important developments in the last years, the best algorithm in the area (PrefixSpan) does not deal with gap constraints and consequently doesn't allow for the introduction of background knowledge into the process. In this paper we present the generalization of the PrefixSpan algorithm to deal with gap constraints, using a new method to generate projected databases. Studies on performance and scalability were conducted in synthetic and real-life datasets, and the respective results are presented

A Tense And Aspect Calculus

This paper focuses on a theory of tense and aspect (the representation of time in natural language) that attempts a formal representation of the relevant linguistic devices as implication rules in first order logic. It presents a rich ontology as far as verb aspect is concerned, distinguishing between complex patterns and vagueness. Examples and conclusions are drawn from the comparison between English and Portuguese, pinpointing the importance of contrastive studies both for the understanding and for the evaluation of a general theory of tense and aspect. In the paper, we present the actual translations of a wide range of phenomena, and a short example. 1 Introduction The method we propose to represent and reason with tense and aspect (T&A) in natural language has several distinguished features: It is both used in the building of the semantic representation of natural language text, and in the inferences allowed from what was actually said. There is therefore no conceptual separa..

Designing Distributed Databases from an Organisational Perspective

In this paper we present a case study of the database system design in the context of an organisation with special emphasis on the replication concern. This case study allows us to identify abstractions and concepts of organisational modelling which are reusable in similar cases. We used the TASKON/OOram method and tool to support the case study development. Keywords: Methodologies and modelling for CoopIS, Systems Integration and Interoperability. 1 Introduction Perceiving organisations in terms of their information systems is a common attitude. The information systems structure, often called schema, gives a partial description of the organisation, which integrated with other such descriptions, is held to be the organisation model. This bottom-up approach for perceiving organisations has been proven to be unsuitable to meet the new challenges faced by organisations: improvement and change in order to constantly adapt to new environment requirements. The bottom-up approach does not o..