Author Archives: Brent

About Brent

Assistant Professor of Computer Science at Hendrix College. Functional programmer, mathematician, teacher, pianist, follower of Jesus.

Pan-Galactic Division in Haskell

Summary: given an injective function , it is possible to constructively “divide by ” to obtain an injection , as shown recently by Peter Doyle and Cecil Qiu and expounded by Richard Schwartz. Their algorithm is nontrivial to come up … Continue reading

Posted in haskell, math, species | Tagged , , , , , , , , , | 6 Comments

Polynomial Functors Constrained by Regular Expressions

I’ve now finished revising the paper that Dan Piponi and I had accepted to MPC 2015; you can find a PDF here: Polynomial Functors Constrained by Regular Expressions Here’s the 2-minute version: certain operations or restrictions on functors can be … Continue reading

Posted in math, writing | Tagged , , , , , , | 5 Comments

Blogging again, & some major life events

It’s been a long time since I’ve written anything here; the blog was on hold while I was finishing my PhD and on the academic job market. Now that things have settled down a bit I plan to get back … Continue reading

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Maniac week postmortem

My maniac week was a great success! First things first: here’s a time-lapse video1 (I recommend watching it at the full size, 1280×720). Some statistics2: Total hours of productive work: 55.5 (74 pings) Average hours of work per day3: 11 … Continue reading

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

Readers wanted!

tl;dr: Read a draft of my thesis and send me your feedback by September 9! Over the past year I’ve had several people say things along the lines of, “let me know if you want me to read through your … Continue reading

Posted in category theory, combinatorics, diagrams, grad school, math, species, writing | Tagged , , , , | 15 Comments

Maniac week

Inspired by Bethany Soule (and indirectly by Nick Winter, and also by the fact that my dissertation defense and the start of the semester are looming), I am planning a “maniac week” while Joyia and Noah will be at the … Continue reading

Posted in grad school, meta, writing | Tagged , , , , , | 9 Comments


This is part four in a series of posts on avoiding the axiom of choice (part one, part two, part three). In my previous post, we considered the “Axiom of Protoequivalence”—that is, the statement that every fully faithful, essentially surjective … Continue reading

Posted in category theory, math, species | Tagged , , , , , , , , , , | 5 Comments