Quick question. Classically the harmonic oscillator Hamiltonian is often written 1 2 ( p 2 + q 2), while quantum mechanically it gets some extra ‘ground state energy’ making the Hamiltonian ...

Did you know that Lawvere did classified work on arms control in the 1960s, back when he was writing his thesis? You can read more here: Yes, that’s right. For technical reasons the n-Category Café ...

• a 2-rig over a field k is a Cauchy complete k -linear symmetric monoidal category is a line object if there’s an object y with x ⊗ y ≅ I. is a bosonic line object if it is a line object and the ...

I’d like to share here a personal project which might be of interest to the readers of this blog: the Clowder Project. Clowder is a wiki and reference work for category theory built using the same ...

guest post by Emily de Oliveira Santos I’d like to share here a personal project which might be of interest to the readers of this blog: the Clowder Project. Clowder is a wiki and reference work for ...

July 2025's Entries The Clowder Project Announcing the Clowder Project: a wiki and reference work for category theory built using the same general infrastructure and tag system of the Stacks Project.

It’s finally here: software that uses category theory to let you build models of dynamical systems! We’re going to train epidemiologists to use this to model the spread of disease. My first talk on ...

Back to modal HoTT. If what was considered last time were all, one would wonder what the fuss was about. Now, there’s much that needs to be said about type dependency, types as propositions, sets, ...

Trivial examples If μ ^ is the mean value of n uncorrelated individuals, then the effective sample size is n. If μ ^ is the mean value of n extremely highly correlated individuals, then the variance ...

Posted by John Baez I keep wanting to understand Bernoulli numbers more deeply, and people keep telling me stuff that’s fancy when I want to understand things simply. But let me try again. The ...