Jeffery Mensah

about

Hello! I'm Jeffery. This site collects my musings and writings on topics I am generally interested in, such as mathematics, music, or software development.

recent posts

Counting symmetric scales in equal-temperament

December 7, 2025∼1250 words

In this post, we give two puzzles related to a concept in music theory referred to as scale symmetry. Roughly speaking, a symmetric scale is a musical scale which does not give a strong impression...

Colimits of presheaves and the density theorem

September 30, 2025∼1000 words

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...

Interpreting adjoint functors

September 17, 2025∼4000 words

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...

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