The Heegner numbers are a good gateway into a brutally ugly and weird corner of analysis, with lots of almost-numbers and almost-facts: https://en.wikipedia.org

The Heegner numbers are a good gateway into a brutally ugly and weird corner of analysis, with lots of almost-numbers and almost-facts: https://en.wikipedia.org/wiki/Heegner_number https://en.wikipedia.org/wiki/Heegner_number In higher (n-)category theory, there is not a single canonical way to describe higher categories, leading to lots of careful use of "strict" and "weak" qualifiers, as well as many different non-equivalent flavors of higher category: https://ncatlab.org/nlab/show/semi-strict+infinity-category https://ncatlab.org/nlab/show/semi-strict+infinity-category Speaking of categories, the number of finite categories, or other finite abstract algebraic objects, is not a beautiful combinatoric theorem, but instead a nasty study of computer-aided searches: https://www.mta.ca/uploadedFiles/Community/Bios/Geoff_Cruttwell/ams2014CruttwellCountingFiniteCats.pdf https://www.mta.ca/uploadedFiles/Community/Bios/Geoff_Cruttw...