mathlib

a7b800ec - doc(overview): small reorganization of algebra/number theory (#5707)

doc(overview): small reorganization of algebra/number theory (#5707) - adds Witt vectors - adds perfection of a ring - deduplicates Zariski topology - moves some items to a new subsection "Number theory" Co-authored-by: Eric Wieser <wieser.eric@gmail.com>