Ribbon Diagrams for Weak Memory

In their POPL'17 paper, Shaked Flur, Susmit Sarkar, Christopher Pulte, Kyndylan Nienhuis, Luc Maranget, Kathy Gray, Ali Sezgin, Mark Batty, and Peter Sewell describe a semantics of weakly-consistent memory that copes (for the first time) with mixed-size memory accesses. In this blog post, I describe how their semantics can be explained rather nicely with some graphical… Continue reading Ribbon Diagrams for Weak Memory

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The Isabelle logo as end-of-proof symbol

In a recent research paper, I formalised some of my theorems in the proof assistant Isabelle, but left some of them as just proved 'by hand'. I found it helpful to use a different 'QED' symbol depending on which method I had used. Below is an enlarged version of the 'three cubes' symbol in the snippet… Continue reading The Isabelle logo as end-of-proof symbol

A proof environment for LaTeX

The johnproof style file provides an environment for typesetting proofs. Features include: It automatically handles page breaks, for those occasions when a long proof splits over multiple pages. It deals with assumptions and case splits. It assigns a label to each step in the proof, for referencing. It indicates the scope of each assumption using… Continue reading A proof environment for LaTeX