Synthetic topos theory

[0028] Type theory of sheaves

Let \(T\) be a type theory and let \(X\) be a topos in \(T\). We introduce the type theory of sheaves on \(X\). It is a type theory internal to \(T\).

[002K] Notation

Let \(T\) be a type theory and let \(X\) be a topos in \(T\). Inside \(T\), the type theory of sheaves on \(X\) is referred to as \(\mathord {\textnormal {\textsf {Sh}}}(X)\).

[002G] Rule

Let \(T\) be a type theory and let \(X\) be a topos in \(T\). Then the type theory of sheaves on \(X\) is a base type theory.

[002H] Rule

Let \(T\) be a type theory and let \(X\) be a topos in \(T\). Then the type theory of sheaves on \(X\) has all products and coproducts.