and indeed addition and the Cauchy product give the category of species a structure much like that of a ring! It’s even more like a ‘rig’, which is a ‘rings without negatives’, since we can add and ...

These are some lecture notes for a 3-hour minicourse I’m teaching at the Summer School on Algebra at the Zografou campus of the National Technical University of Athens. To save time, I am omitting the ...