The symbol ≅ is used for isomorphism of objects of a category, and in particular for isomorphism of categories (which are objects of CAT). The symbol ≃ is used for equivalence of categories. At least, this is the convention used in this book and by most category theorists, although it is far from universal in mathematics at large.
$\\mathbb Q$ is used to represent rational numbers. $\\mathbb R$ is used to represent reals. Is there a symbol or convention that represents irrationals. Possibly $\\mathbb R - \\mathbb Q$?
There is a common thread running through many of the mysteries and hints in the series—the mysterious symbol, (alleged) astronomical symbols, cannibalism, and the sign of the bird and water symbolism in Episode 8. This thread also runs through questions with seemingly obvious answers, especially, “Why is the series called Yellowjackets?” It all boils down to trigonometry, occultations ...
An unsophisticated question from a neophyte: Given the numbers: $1,2,3,4,5$ What is the symbol for the range of the numbers? i.e. the lowest-highest number in the set. For example, the min max ...
It looks like a variation on the right-facing Armenian eternity symbol "֍" The sign is an ancient Armenian national symbol often carved on khachkars and on walls of churches, symbolizing the concept of everlasting, celestial life. I'm unsure of the choice of the hexagon in the center of it though possibly efficiency, use of space or materials, balance, unity, symmetry, sacred geometry, a ...
