Of all the endless questions children and mathematicians have asked about infinity, one of the biggest has to do with its size. Whether it’s on the playground or at bedtime, children encounter the ...

The discussion on Tom’s recent post about ETCS, and the subsequent followup blog post of Francois, have convinced me that it’s time to write a new introductory blog post about type theory. So if ...

Then K K is the category of substructures of a countable structure M M which is universal and homogeneous. Examples include the Rado graph as the Fraïssé limit of the category of finite graphs and ...