Illustrating the Mezzo programming language

When programmers want to prove strong program invariants, they are usually faced with a choice between using theorem provers and using traditional programming languages. The former requires them to provide program proofs, which, for many applications, is considered a heavy burden. The latter provides less guarantees and the programmer usually has to write run-time assertions to compensate for the lack of suitable invariants expressible in the type system. We introduce Mezzo, a programming language in the tradition of ML, in which the usual concept of a type is replaced by a more precise notion of a permission. Programs written in Mezzo usually enjoy stronger guarantees than programs written in pure ML. However, because Mezzo is based on a type system, the reasoning requires no user input. In this paper, we illustrate the key concepts of Mezzo, highlighting the static guarantees our language provides

The problematic art of illustrating 'Moxon's Tennyson'

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Illustrating Stability Properties of Numerical Relativity in Electrodynamics

We show that a reformulation of the ADM equations in general relativity, which has dramatically improved the stability properties of numerical implementations, has a direct analogue in classical electrodynamics. We numerically integrate both the original and the revised versions of Maxwell's equations, and show that their distinct numerical behavior reflects the properties found in linearized general relativity. Our results shed further light on the stability properties of general relativity, illustrate them in a very transparent context, and may provide a useful framework for further improvement of numerical schemes.Comment: 5 pages, 2 figures, to be published as Brief Report in Physical Review