Hawk solutions to the TTC 2018 Social Media Case

The TTC 2018 Social Media Case required answering queries about social networks, where people write posts, comment on them, and friend or unfriend each other. NoSQL databases have been popular in the analysis of large social networks, and the Hawk heterogeneous model indexer can turn the models in the case to Neo4j NoSQL databases. This paper presents three solutions that were developed on top of each other, reducing on each step the amount of work required to update the results of the query

Instance Generation from Type Graphs with Arbitrary Multiplicities

Meta modeling is a wide-spread technique to define visual languages, with the UML being the most prominent one. Despite several advantages of meta modeling such as ease of use, the meta modeling approach has a major disadvantage: It does not offer a direct means for generating its language elements. This disadvantage poses a severe limitation on certain applications. For example, when developing model transformations, it is desirable to have enough valid instance models available for large-scale testing. Producing such a large set by hand is tedious. In the related problem of compiler testing, a string grammar together with a simple generation algorithm is typically used to produce words of the language automatically. In this paper, we formalize a restricted form of meta-models by type graphs with multiplicities and introduce instance-generating graph grammars for creating instance graphs representing the abstract syntax structures of models. Thereby, a further step is taken to overcome the main deficit of the meta-modeling approach

Interim research assessment 2003-2005 - Computer Science

This report primarily serves as a source of information for the 2007 Interim Research Assessment Committee for Computer Science at the three technical universities in the Netherlands. The report also provides information for others interested in our research activities