Aspects Of Finiteness
Peter T. Johnstone · 2002
Abstract The definition and some of the basic properties of natural number objects in a topos were introduced in Section A2.5. However, there were some important properties which could not be developed there because they required the ability to interpret higher-order logic in a topos. Having developed the techniques for this in the previous chapter, we are now ready to return to the study of natural number objects and complete what we left unfinished in Section A2.5.