Jeffery Mensah

The goal of this short note is to show how to compute the limit or colimit of a diagram of presheaves, and prove that every presheaf can be written as the colimit of representable...

The notion of an adjunction between categories is a fundamental idea in category theory whose utility is so great that it appears in virtually every field of mathematics. Roughly speaking, an adjunction is...

The $\mathrm{Tor}$ functors, which are ubiquitous in algebraic topology and more generally homological algebra, encode the failure of the tensor product to be an exact functor. As a derived functor, one typically defines...