Let \(T\) be a type theory.
We work in \(T\).
Let \(i:\mathord {\textnormal {\textsf {Level}}}\)
and let \(X\) be a topos.
We define the
global section functor
\(\Gamma _{X}:\mathcal {S}(X,i)\rightarrow \mathcal {U}(i)\)
by the following composite.
\(\mathcal {S}(X,i)\)\(\simeq \) {[003G]}\(\mathord {\textnormal {\textsf {D}}}_{\mathord {\textnormal {\textsf {Sh}}}(X)}({}\vdash \mathcal {U}(i))\)\(\rightarrow \) {\(\mathord {\textnormal {\textsf {GS}}}_{\mathord {\textnormal {\textsf {Sh}}}(X)}\)}\(\mathcal {U}(i)\)
By
[002R],
\(\Gamma _{X}\)
has a left adjoint
which we call the
constant sheaf functor
and is denoted by
\(\Delta _{X}\).