Tom van der Zanden

Welcome to my home page! On June 26^th, I defended my PhD thesis "Theory and Practical Applications of Treewidth" (pdf), which I completed under the supervision of Hans Bodlaender at Utrecht University. I am interested in the theory and applications of graph algorithms (specifically those involving treewidth) and parameterized and exact complexity. As a hobby, I design and make 3D printed puzzles (and recently, other 3D printed and electronic gadgets). As of October 2019, I am Assistant Professor in Algorithms and Optimisation at the Department of Data Analytics and Digitalisation of Maastricht University.

You can reach me via my institutional mail (T.vanderZanden@maastrichtuniversity.nl) or personal email address (tom@tomvanderzanden.nl).
If you would like to buy one of my puzzles, you can do so in my Shapeways shop (beware of sticker shock, Shapeways has regretfully raised their prices a lot compared to what they used to be).

Publications

Google Scholar - dblp

Below is a list of my (peer-reviewed) conference publications.

On Exploring Always-Connected Temporal Graphs of Small Pathwidth - joint work with Hans Bodlaender. Information Processing Letters (2019). arXiv

Flower power: Finding Optimal Flower Cutting Strategies Through a Combination of Optimization and Data Mining - joint work with Han Hoogeveen and Jakub Tomczyk. Computers & Industrial Engineering (2019).

Subgraph Isomorphism on Graph Classes that Exclude a Substructure - joint work with Hans Bodlaender, Tesshu Hanaka, Yoshio Okamoto and Yota Otachi. CIAC 2019, to appear.

Stable Divisorial Gonality is in NP - joint work with Hans Bodlaender and Marieke van der Wegen. SOFSEM 2019. arXiv

On the Exact Complexity of Polyomino Packing - joint work with Hans Bodlaender. FUN 2018.

Framework for ETH-tight algorithms and lower bounds in geometric intersection graphs - joint work with Mark de Berg, Hans Bodlaender, fellow PhD-student Sándor Kisfaludi-Bak and Daniel Marx. STOC 2018. arXiv

Complexity of the Maximum k-Path Vertex Cover Problem - joint work with Eiji Miyano, Toshiki Saitoh, Ryuhei Uehara and Tsuyoshi Yagita. WALCOM 2018.

Computing Treewidth on the GPU - joint work with Hans Bodlaender. IPEC 2017. arXiv

On the Exact Complexity of Hamiltonian Cycle and q-Colouring in Disk Graphs - joint work with Sándor Kisfaludi-Bak. CIAC 2017.

Improved Lower Bounds for Graph Embedding Problems - joint work with Hans Bodlaender. Best paper award at CIAC 2017. arXiv

On the Maximum Weight Minimal Separator - joint work with Tesshu Hanaka, Hans Bodlaender and Hirotaka Ono. TAMC 2017.

Subexponential Time Algorithms for Embedding H-Minor Free Graphs - joint work with Hans Bodlaender and Jesper Nederlof. ICALP 2016.

Parameterized Complexity of Graph Constraint Logic - single author paper. IPEC 2015. arXiv

PSPACE-Completeness of Bloxorz and of Games with 2-Buttons - joint work with Hans Bodlaender. CIAC 2015. arXiv

According to google scholar, my H-index is 5. My Erdős number is 3 (via Hans Bodlaender); my Erdős lap number is 4 (via Ryhuei Uehara).

Software

PartStacker - Create tight packings of (puzzle) parts to minimize the cost of having them 3D printed.

SteinerTreeTW (github) - Steiner Tree solver using dynamic programming on tree decompositions. Submission to the PACE 2018 challenge (third place).

GPGPU Treewidth (github) - Compute tree decompositions on a GPU. Associated paper at IPEC 2017.

BZTreewidth (github) - Solver for computing tree decompositions. Submission to the PACE 2016 challenge (second place).

Teaching

I am very interested in teaching. My current teaching duties at Utrecht University include assisting in the Algorithms course and in the Concurrency course.
For the algorithms course, I lead the working classes and handle the practical programming assignments through the automatic grading system DomJudge (thinking up the assignments, generating test cases, writing a reference solution and helping the students debug their code).
For concurrency, I also lead the working classes and handle the practical programming assignments through a DomJudge knockoff called "TomJudge" (which includes some features specific to concurrency, such as automatically measuring whether the program executes faster given more cores).
I also am the administrator of our department's DomJudge installation, which, besides its use in algorithms, is also used in many other courses. I help lecturers set up their assignments, handle any problems that come up, and occasionally develop new features. I recently gave a presentation on our use of DomJudge at the Dutch ICT education symposium NIOC 2018.

Puzzles

Below you can see some of the puzzles that I have designed. You can click on a puzzle to get more information about it. Each of these puzzles was designed using 3D CAD software, and then printed by Shapeways in Nylon using Selective Laser Sintering (SLS). I dye the puzzles myself (using dylon ebony black dye) and make my own stickers on a plotter. Note that several of these puzzles have been mass produced (either by Mefferts, MF8 or Calvin's Puzzles).