Flotsam on Tom Harris

Associahedron

tkmharris@protonmail.com (Tom Harris) — Sat, 12 Feb 2022 00:00:00 +0000

Jean-Louis Loday’s realisation of the (5-)associahedron:

The vertices are generated from planar binary trees using the algorithm described in Loday’s paper¹ (Loday gives vertices in 4-space but they sit in a 3-dimsional hyperplane which I’ve projected onto ordinary 3-space). The surface was created and written to STL with the Trimesh Python library. Code.

Loday, J-L. Realization of the Stasheff polytope. Archiv der Mathematik 83, 267–278 (2004). doi ↩︎

Fimmvörðuháls

tkmharris@protonmail.com (Tom Harris) — Sat, 21 Aug 2021 00:00:00 +0000

Fimmvörðuháls, June 2017.

Herb

tkmharris@protonmail.com (Tom Harris) — Sat, 22 May 2021 00:00:00 +0000

From an amazon.com review of Lewis & Papadimitrious’s Elements of the Theory of Computation:

And also… who the hell is this geek on the cover? It doesn’t reveal his identity anywhere in the book. You know this book is bad when they have a herb like him staring at you. This guy needs a new suit, a haircut, and he needs to learn how to smile.

The herb

Latin Wiphala

tkmharris@protonmail.com (Tom Harris) — Tue, 04 May 2021 00:00:00 +0000

I’ve been playing with Latin squares today. Here is a wiphala arranged in the pattern of the 7 by 7 Latin square used on the cover of Ronald Fisher’s The Design of Experiments.

Haskell Akiyama–Tanigawa

tkmharris@protonmail.com (Tom Harris) — Sat, 01 May 2021 17:03:32 +0100

I am a big fan of the Akiyama–Tanigawa algorithm¹² for computing Bernoulli numbers. It works by generating a structure resembling Pascal’s triangle, with rows whose entries are determined by a simple calculation on the two entries above them, from which we can read off the sequence of Bernoulli numbers.

What I like about this algorithm, besides its simplicity and elegance, is that it admits a concordantly simple and elgant implementation in Haskell using infinite data structures.