We introduce a nonstandard arithmetic NQA− based on the theory developed by R. Chuaqui and P. Suppes in [2] (we will denote it by NQA+ ), with a weakened external open minimizati...
We show how to interpret the language of first-order set theory in an elementary topos endowed with, as extra structure, a directed structural system of inclusions (dssi). As our ...
Steven Awodey, Carsten Butz, Alex Simpson, Thomas ...