Sebastian at home, 17 September 2015.
This is a very painful article to write and, for all those that knew Sebastian, I feel sure it is equally hard to read. On Sunday, 8 November, at 9:50 in the morning and following a brief, but intense, illness, my friend, colleague and Director of research at TCIDA (the Tungsten Centre for Intelligent Data Analytics) passed away. To say this shocked me and all his colleagues at TCIDA is an understatement, for Sebastian played a huge role in both the process of building TCIDA at Goldsmiths and subsequently in running and driving its core research - not so say supervising graduate student(s), making coffee, drinking wine and bringing forth laughter - that it is difficult to imagine life at the centre continuing to move ahead without him.
From a purely personal perspective, Sebastian was the first friend I made at Goldsmiths when I arrived in 2003, and has been a good friend and mentor to me ever since. Together we worked on a large (three grant) KTP which successfully developed the "SpendInsight system" for @UK PLC; this was software subsequently deployed by the UK National Audit Office (NAO) to identify over £500m p/a in potential savings in the NHS procurement budget and which paved the foundations for a continuing interest in data analytics (specifically, with respect to purchasing); a shared interest which eventually led to discussions with Tungsten Corporation in autumn 2013 and the eventual launch of the TCIDA centre at Goldsmiths in March 2015.
The first six months working at TCIDA with Sebastian and our team have been amongst the most enjoyable and productive of my academic life; all experiences I know Sebastian fully shared. It is just so sad that Sebastian, having spent so long working to get the centre financed and finally firing on all cylinders, had so little time to enjoy the fruits of our long preparations.
But Sebastian hasn't always worked in Artificial Intelligence and Data Science; for most of his academic life he has been helping to drive forward the foundations of static program analysis (in particular, program slicing) - a new theoretical approach to analysing software. His core colleagues in the area - Dr John Howroyd (TCIDA) and Prof Mark Harman (UCL) - summarise Sebastian's technical achievements in this area.
Sebastian obtained his PhD in 1999 for a thesis entitled Dataflow minimal slicing, which analysed the theoretical foundations of dependence in software systems. Understanding the way in which one computation can affect another in a software system is fundamental to many problems faced by software developers, such as testing, compiler optimisation and improving the behaviour of the software system. Sebastian's work laid theoretical foundations for understanding this dependence, and he developed "slicing" algorithms for computing various different forms of dependence to support the analysis of software systems at various levels of abstraction.
Shortly before his sudden and untimely death, he had developed a highly original, elegant and important way to finally fully understand control dependence (the way in which the outcome of one computation can decide whether another takes place or not). This is a seminal piece of work and will undoubtedly become a landmark result. His work was well known within the scientific community and used by several companies including Daimler and @UK PLC.
Seb brought every piece of his heart to his work and he taught with passion. He befriended his students: they respected him and he returned that respect. He cared. His strong bond with those he taught is shown most clearly in the success of his PhD students, all of whom not only completed with Seb's guidance but who also became his friends. If you were a PhD student of Seb's you could be guaranteed unending support, help, wine and good food. He was always there for his colleagues too - a good listener who liked to add a hefty dose of his own acerbic jokes, putting everything in perspective and delighting in mischievous wit. His warmth and affection is recalled by all who loved him. He had the gift of openness and genuine charm. Sebastian is a loss to the department not just in terms of his intellect but also because he was a person so full of life that it seems inconceivable that he is gone from it.
In summary, as well as his scientific contributions, those who worked with Sebastian all fondly remember him as an exceptionally imaginative and creative intellect. He was an accomplished cellist and regularly held musical events, quartet recitals and musical soirees at his house; I am sure Sebastian's musician friends are also bereft. In addition Sebastian brought an infectious, slightly mischievous, humour to his scientific and technical conversations and to the social life that surrounded them. He was an inspirational lecturer and loved teaching students how to program and the technical details of algorithm design. Sebastian will be sorely missed by all those who knew him.
Mark Bishop (TCIDA), Mark Harman (UCL), John Howroyd (TCIDA), Robert Zimmer (Computing, Goldsmiths), Lahcen Ouarbya (Computing, Goldsmiths), Kate Devlin (Computing, Goldsmiths)