Archive

Pages from earlier versions of this site, kept because their URLs are linked from elsewhere and because some of them are still occasionally useful. They are not maintained, they are not in the site navigation, and they do not represent current work.

Every page here is at the URL it always had. Nothing was moved to get it into this list.

Formalization notes (2020–2021)

Early notes on formalizing universal algebra in Agda, written while working out the approach that became agda-algebras. They are superseded by that library and its documentation, and are kept as a record of how the ideas developed rather than as a reference.

• The Agda UALib — index of the notes
• Birkhoff's HSP theorem
• Composition of relations
• Elementary facts
• F-algebras
• Relations

Teaching materials: linear algebra in Sage (2019)

Lab assignments for a linear algebra course, written against the department's Sage server. That server is long gone, so the sign-in instructions no longer apply, but the worksheets themselves still work in any Sage installation.

• Linear algebra in Sage — index
• Lab 1 · Lab 2 · Lab 3 · Lab 4
• Computer lab and Lab 01
• Exporting from Sage

Talks

• Varieties of algebras and their logics — notes for a 2020 talk

Posts

Older posts kept outside the blog's main line. The blog itself is at /blog/.

• Type theory and functional programming (2014) — a reading group announcement
• A probability quiz (2014) — an interview puzzle, worked through
• Touchpad forensics (2021) — debugging a laptop touchpad on Linux

Not here yet

The CSP research notes at /research/csp/ are missing from this list. They link five third-party published papers whose redistribution has not been settled, so the pages stay out rather than shipping with dead links or with someone else's PDFs. See #67.