Monthly Archives: November 2010

Species subtraction made simple

Posted on November 24, 2010 by Brent

> {-# 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 , , , , , , , | 15 Comments

Things I have learned about vector spaces

Posted on November 20, 2010 by Brent

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?

Posted on November 18, 2010 by Brent

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