I am most interested in similarity search, which is the activity of finding objects, from within a collection, which are most similar to another object presented as a query. This requires a represention of the objects in a mathematical (metric) space, and a formally defined metric as a proxy for the real-world notion of similarity. That becomes really interesting when the objects are complex (eg images, video, etc) and the space is large - and by large we mean hundreds of millions, or maybe billions. If you know that a billion milliseconds is around ten days, you'll realise we need to do clever things to avoid an exhaustive search of the space!

Surprisingly, or maybe not, the difficult issues in this domain require research in high-dimensional abstract geometry. I am currently actively working in: subclasses of metric space, for example those with Ptolemaic or Hilbert properties; angle distribution in high-dimensional non-Euclidean spaces; approximate search and locality sensitivity; asymmetric permutation orderings, and, most recently, inverted indexes and decodable Bloom filters. I'd love to give a simple overview for the lay reader but, as it says on the mug, "I think you'll find it's a bit more complicated than that!"

I started my "Computational Science" degree in St Andrews in 1981. I stayed here until 1996... doing a BSc, a PhD (in Ron Morrison's research group), various research jobs, and an SERC Postdoc Fellowship. After that I held an EPSRC Advanced Fellowship at Glasgow, a chair at Strathclyde (including spells as Director of Research and Head of Department), moved to Stirling in 2018 to head up the Division of Mathematics and Computer Science, and returned to St Andrews in 2020. Outside academia I've been quite involved with the commercialisation of research - with Reuters, when it existed, and a couple of hi-tech startups - Engimatec (now defunct!) and Cloudsoft (still operating in Edinburgh). I have also been involved in school-level CS education, am a co-author of Education Scotland's computing curriculum, and am the technical validator for SQA computing qualifications.

I teach CS4103, Distributed Systems, as well as various project supervision and first-year programming tutorials.

similarity and metric search, high-dimensional geometry, Hilbert spaces, dimensionality reduction