Homepage of Alexander Paar

last update: 03/14/2014

Programming the Semantic Web

In recent years, Semantic Web technologies such as RDF(S) and the Description Logics based Web Ontology Language (OWL DL) have paved the way for standardized formal conceptualizations of all kinds of knowledge. Numerous ontologies have been developed to conceptualize a plethora of domains of discourse.

Since corporations from all sectors have braced to define company specific knowledge using Semantic Web technologies, ontology engineering has become a business model for a number of companies. As the underlying standards have matured, tools for ontology engineering have emerged both in commercial as well as in academic fields.

Knowledge acquisition systems such as Protégé make it particularly easy to construct domain ontologies and to enter data. Ontology management systems such as Jena can be used for creating, modifying, querying, and storing ontologies. Inference engines such as Pellet provide support for automatic reasoning. There is an incessantly growing set of tools, projects, and applications for ontology languages like OWL.


...processing ontological information programmatically is still laborious and error prone. From my experience, this is mainly caused by the lack of compile time support both for XML Schema Definition (XSD) type definitions, which may be the range of OWL data type properties, as well as for terminological knowledge in form of ontologies.

I am developing the novel programming language Zhi#, which provides compile time and runtime support for XSD and OWL.

Consider yourself personally invited to have a go at this new tool!

Use-Case Responsibility Driven Analysis and Design

Use-Case Responsibility Driven Analysis and Design (URDAD) is a services-oriented analysis and design methodology for domain experts to develop semi-formal requirements and technology-neutral design models. I am contributing to the consistency and completeness properties of the URDAD MDE metamodel.

The URDAD MDE research project is co-funded by the South African National Research Foundation (NRF) in the THRIP program.

Computers in the Human Interaction Loop

The goal of the CHIL project was to make everybody’s daily life easier. CHIL was an integrated European research project with 15 project partners in Europe and in the US aiming to bring friendlier and more helpful computing services to society. Rather than requiring user attention to operate machines, CHIL services attempt to understand human activities and interaction in order to provide helpful services implicitly and unobtrusively. In CHIL, socially supportive environments proactively support human gatherings. Such environments offer, for example, meeting assistants that track and summarize human interactions in lectures, meetings, and office interactions.

The CHIL Ontology was developed to provide a formal high level description of the CHIL domain of discourse that can be efficiently used to build intelligent applications. As such, the CHIL ontology introduces a common programming language agnostic object model that can be used to formally represent elements of the CHIL domain of discourse. By using the Description Logics based Web Ontology Language (OWL DL) to model concepts, roles, and individuals of the CHIL domain of discourse it is possible to use a reasoner in order to automatically make implicit knowledge explicit, which can actually be considered as a form of artificial intelligence.

CHIL was co-funded by the European Union through the Information Society Technologies (IST) priority in the Sixth Framework Program.

MorphoSys SIMD Predication

MorphoSys is a reconfigurable computer architecture that is composed of a software programmable processing unit called TinyRISC and a reconfigurable hardware unit called Reconfigurable Cell Array (RC Array). The Reconfigurable Cell Array has 64 reconfigurable cells arranged in an 8 by 8 array. Each cell has an ALU/MAC unit and a register file. RC Array functionality and the interconnection network are configured through context words. Context words are stored in a context memory in two blocks (one for the rows and the other one for the columns). Each block has eight sets of sixteen context words.

I developed a novel branch predication scheme for the MorphoSys Reconfigurable Cell Array by improving and combining the unrestricted predication model and the guarded execution model. It could be shown that significant execution autonomy was added to the SIMD processing elements and that the code size was reduced considerably. The implemented predication scheme enables more efficient if-conversion compilations than previous predication schemes of general purpose processors.

This work was supported by DARPA (DoD) under contract F-33615-97-C-1126 and the National Science Foundation under grant CCR-0083080.

The BTRC Remote Control System

The Universal Bluetooth Remote Control System (BTRC) was a contribution to the 2001 IEEE Computer Society International Design Competition. The BTRC system enables devices to communicate over various transport protocols, allowing them to be controlled remotely using either a GUI, plain text messages, hyperlinks or speech. Exiting BTRC use cases include: With a BTRC-powered universal remote control you can use completely wireless technology to voice-operate your VCR in your living room at home while you are in your office at work. Via speech recognition you can set up the universal remote control to build a list of devices that are near your current location and/or are of general interest to you.

BTRC pursues a simple vision to make interaction with electronic devices less obtrusive and our everyday life more convenient:

"Any device, from anywhere - at any time!"

C# + XSD + OWL = Zhi#

The Zhi# programming language boasts compiler and runtime support for XSD and OWL.


CHIL Knowledge Base Server

The CHIL Knowledge Base Server is an adapter for existing ontology management systems.

CHIL Knowledge Base Server


From 2010-2011 I contributed to the South African research project Use-Case Responsibility Driven Analysis and Design.



From 2003-2007 I contributed to the European research project Computers in the Human Interaction Loop.



I contributed to the MorphoSys research project at the Department of Electrical & Computer Engineering at University of California, Irvine.



The Universal Bluetooth Remote Control System (BTRC) was a contribution to the 2001 IEEE Computer Society International Design Competition.