Monthly Archives: November 2010

Species subtraction made simple

> {-# OPTIONS_GHC -fno-warn-missing-methods #-} > module Virtual where > > import Control.Applicative > import Test.QuickCheck Yesterday on #haskell, augur asked me to explain how subtraction works for combinatorial species. (For an introduction to species, see my paper from the … Continue reading

Posted in combinatorics, haskell | Tagged , , , , , , , | 14 Comments

Things I have learned about vector spaces

Work on the diagrams library is coming along rather nicely. I’ll have more to say about it soon, but for now here are two things I have learned recently: Normals transform as the inverse transpose (see Subject 5.27). Be very … Continue reading

Posted in math, projects | Tagged , , , , , , , | 4 Comments

Minimal test case generator tool?

An interesting idea that Daniel Wagner, Vilhelm Sjöberg and I just came up with: a minimal test case generator. Here’s the idea: you have a program which exhibits error X, which you want to understand better; or perhaps you suspect … Continue reading

Posted in meta | Tagged , , , , , , | 9 Comments