Categorifying cardinal arithmetic [pdf]

This is a pleasant but intentionally very elementary summary of the relevant concepts. If you're interested in much more on this, one place to start is MO (https://mathoverflow.net/questions/4841/what-precisely-is-ca...), or the n-Category Café (https://golem.ph.utexas.edu/category/2008/10/what_is_categor...), or Baez's TWF 121 (http://math.ucr.edu/home/baez/week121.html).

Warning: all are much math-ier than Riehl's very nice slides, although the first one has enough content that you may find an answer that you like. If your math itch still isn't scratched, there's Baez and Dolan's paper "Categorification" (https://arxiv.org/abs/math/9802029). I don't know a programmer-focussed view on categorification; can anyone recommend one?

PDF slide builds really don’t work for the web.