
Chains of Preorders
I show how long the longest chain of preorders on a set is. This problem comes up when analysing the query complexity of the NL* algorithm (and generalisation thereof). As a surprise the triangular numbers pop up!

Vector Spaces with Atoms
In a recent paper we introduced vector spaces with atoms. In this post I will show some of the underlying maths and discuss why, for register automata, weights are nicer than nondeterminism.

Residual probabilistic automata are not closed under convex sums
Just a quick counterexample.

Separation and Renaming in Nominal Sets
Some notes on our paper "Separation and renaming in Nominal Sets."

PD is not a monad. So What‽
What does it really mean when something is not a monad, and should we care? Specifically, I will look at nondeterminism and probabilistic choice.

Gradient Descent on pWFAs
Solving the parameter synthesis problem with a gradient descent. Or; computing the derivative of a parametric weighted automaton.

L* Learning of pWFAs
In my previous post, I defined parametric weighted automata, which are WFAs where we allow parameters on transitions. Can we use L* to learn the structure of these automata?

Parametric Weighted Automata
I moved to Aachen for a postdoc on probabilistic programs. This means that I am learning about new, exciting topics. I will collect notes on this blog, as they may be useful to others. One of the research lines here is that of parametric Markov chains. This post shows how to use weighted automata in this context.

Why is learning so effective in software testing?
The Communications of ACM recently published an article on automata learning in software engineering. The techniques described in the article are used to obtain models for the behaviour of software. Even without access to source code, one can now use model checking or other bug finding tools on these models. The article shows many successful applications. Why is this possible at all?

My Raspberry Pi setup
A quickstart for headless Raspbian setup with shairport and WiFi.

Gravity Beats multiuser experience!
Yesterday there was Sound of Science, an cultural event at the Radboud University in Nijmegen. People from the event asked me to present my app Gravity Beats there, because it is about sound and a bit about gravity ;). Instead of just showing my iPad app, I wanted something more, so I created a collaborative version in which multiple users could draw the lines.

One game a month (update)
It involved procedurally generated planets, cows (with homemade sound) and explosions!

Gravity Beats now in appstore!
The app I made in the last two months has been approved by Apple. So you finally can play around with it on your own iPad; get it from the Appstore!

One game a month
This year something cool; every month we will release a game (or something which looks like a game), together with Astrant.

Zen Zoom released!
I just released a new app; Get it on the Appstore. It is a gimmick drawing app, based on some fancy OpenGL shaders I created for the desktop.