Roberto V. Zicari

PoliTwi: early detection of emerging political topics on twitter and the impact on concept-level sentiment analysis

In this work, we present a system called PoliTwi, which was designed to detect emerging political topics (Top Topics) in Twitter sooner than other standard information channels. The recognized Top Topics are shared via different channels with the wider public. For the analysis, we have collected about 4,000,000 tweets before and during the parliamentary election 2013 in Germany, from April until September 2013. It is shown, that new topics appearing in Twitter can be detected right after their occurrence. Moreover, we have compared our results to Google Trends. We observed that the topics emerged earlier in Twitter than in Google Trends. Finally, we show how these topics can be used to extend existing knowledge bases (web ontologies or semantic networks) which are required for concept-level sentiment analysis. For this, we utilized special Twitter hashtags, called sentiment hashtags, used by the German community during the parliamentary election.

Incomplete information in object-oriented databases

We present a way to handle incomplete information both at schema and object instance level in an object-oriented database. Incremental schema design becomes possible with the introduction of generic classes. Incomplete data in an object instance is handled with the introduction of explicit null values in a similar way as in the relational and nested relations data models.

Typed Sets as a Basis for Object-Oriented Database Schemas

The object-oriented data model TM is a language that is based on the formal theory of FM, a typed language with object-oriented features such as attributes and methods in the presence of subtyping. The general (typed) set constructs of FM allow one to deal with (database) constraints in TM.The paper describes the theory of FM, and discusses the role that set expressions may play in conceptual database schemas. Special attention is paid to the treatment of constraints, and a three-step specification approach is proposed. This approach results in the formal notion of database universe stated as an FM expression.

Algres: an advanced database system for complex applications

A description is given of Algres, a programming environment that extends the relational model to handle complex objects and operations and integrates the logic programming paradigm. Algres is designed to be used to develop knowledge bases, software-engineering systems, office-automation systems, and computer-aided design and manufacturing databases. The discussion covers the Algres components, its data model, the RA abstract machine, and user languages. The system is written entirely in C. >

The role of polymorphic reuse mechanisms in schema evolution in an object-oriented database

A seamless approach to the incremental design and reuse of object oriented methods and query specifications is presented. We argue for avoiding or minimizing the effort required for manually reprogramming methods and queries due to schema modifications, and demonstrate how the role of polymorphic reuse mechanisms is exploited for enhancing the adaptiveness of database programs against schema evolution in an object oriented database. The salient features of our approach are the use of propagation patterns and a mechanism for propagation pattern refinement. Propagation patterns are employed as an interesting specification formalism for modeling operational requirements. They encourage the reuse of operational specifications against the structural modification of an object oriented schema. Propagation pattern refinement is suited for the specification of reusable operational modules. It promotes the reusability of propagation patterns toward the operational requirement changes. This approach has a formal basis and emphasizes structural derivation of specifications. The main innovations are in raising the level of abstraction for behavioral schema design, and for making possible the derivation of operational semantics from structural specifications. As a result, both the modularity and reusability of object oriented schemas are increased.

Building and evaluating nonobvious user profiles for visitors of Web sites

Building profiles of registered users of a Web site, as in case of a portal, is of importance if it goes beyond collecting the obvious information the user is willing to give at the time of registration. The starting point of this work is the assumption that a community of users is registered on a Web site and that for each user a profile is built. Such a profile contains two parts of data: one obvious, given directly by the user and one less obvious, inferred by the users behavior during his visits on the site. This paper presents ideas on how to build a user profile based on nonobvious information and takes into account various factors influencing in its development. Special emphases are paid on feedback mechanism and several methods of measuring its results.

Creating User Profiles of Web Visitors Using Zones, Weights and Actions

In this paper, we report our experience in the implementation of a module for creating user profiles of Web visitors by using Zones, Weights and Actions. The module is part of Gugubarra 2.0, a tool for better understanding and management of communities of registered Web visitors, currently being developed by the database group at the Computer Science Institute of the Goethe University in Frankfurt. In addition we introduce a semantic concept for our approach.

Correctness of Lazy Database Updates for Object Database Systems

Current object database management systems support user-defined conversion functions to update the database once the schema has been modified. Two main strategies are possible when implementing such database conversion functions: immediate or lazy database updates. In this paper, we propose a correctness criteria for implementing conversion functions as lazy database updates. We also show that the algorithms defined in [1] are correct.

The Design of Gugubarra 2.0: A Tool for Building and Managing Profiles of Web Users

We have introduced the concept of non-obvious user profiles (NOPs) to capture the hypothetical interest of Web users. In this paper we present the design principles and rules of our Gugubarra engine, which is a tool to calculate and visualize these non-obvious user profiles

On Clustering Visitors of a Web Site by Behavior and Interests

This paper addresses the issue of how to define clusters of web visitors with respect to their behavior and supposed interests. We will use the non-obvious user profiles (NOPs) approach defined in [10], and present a new clustering algorithm which is a combination of hierarchical clustering together with a centroid based method with priority, which allows to cluster web users by similar interest in several topics.