# Visualising air quality data with Voronoi diagrams

An extended version of a lightning talk I’ll be giving on the subject of Voronoi diagrams: what they are, where they come from, and how we can use them to visualise (some) geographic data sets.

Slides or other notes for formal presentations given by me.

An extended version of a lightning talk I’ll be giving on the subject of Voronoi diagrams: what they are, where they come from, and how we can use them to visualise (some) geographic data sets.

I attended the 2013 Joint Mathematics Meetings in San Diego to present work at the AMS-SIAM Special Session on Mathematics of Computation: Algebra and Number Theory, II. Here are my slides, on Lehmer’s conjecture for Hermitian matrices over the Eisenstein and Gaussian integers.

I gave the Number Theory Seminar at the Department of Pure Mathematics, University of Waterloo on Thursday, September 8th. My slides are available in presentation or handout form (except the latter is missing the interlacing demo which didn’t render into individual slides correctly). I used this talk as an opportunity to present some results that …

Continue reading ‘Cyclotomic Matrices and Graphs: Waterloo’ »

I’m continuing to tour my Cyclotomic Matrices and Graphs talk; today I presented it at the University of Warwick. Here’s the latest and greatest iteration of the slides, mostly unchanged except for the current state of the computer search for minimal noncyclotomics of at most ten vertices. I’d hoped to finish that this month, but …

Continue reading ‘Cyclotomic Matrices and Graphs: Warwick’ »

I’m speaking this afternoon at the Heilbronn Seminar in Bristol: my slides are available here. This is essentially (up to permutation, and modulo errors!) the talk I gave at Royal Holloway in October, although the last few slides have been replaced with a result I’ve found since then. I try to avoid technical details of …

Continue reading ‘Talks on Cyclotomic Matrices and Graphs’ »

I’m back from the Fields Institute in Toronto, where I spoke at the above workshop, on my usual topic of cyclotomic and 4-cyclotomic matrices/graphs. During the talk I described my conjecture that a graph is maximal cyclotomic if-and-only if it’s 4-cyclotomic, and after an hour at the blackboards with James McKee I now have a …

Continue reading ‘Workshop on Discovery and Experimentation in Number Theory’ »

Tomorrow, in what seems to be becoming an annual tradition, I’ll be giving a talk on cryptography at the Geometry Club. Since it’ll be a talk-and-chalk style seminar, I don’t have any slides to make available, but many of the topics I’ll be discussing have appeared earlier on this blog or everything2. In particular, I’m …

Continue reading ‘Geometry Club Talk: Why Cryptography Doesn’t Guarantee Security’ »

Slides for a talk on cyclotomic matrices/graphs given at the MAGIC conference in Manchester.

Slides from a colloquium I gave on public key cryptography.

Notes from my geometry club talk given April 18th, 2008.