mathlib

7e1ef9f8 - feat(ring_theory/witt_vector): assorted facts about Witt vectors over char p rings (#12093)

feat(ring_theory/witt_vector): assorted facts about Witt vectors over char p rings (#12093) Co-authored-by: Heather Macbeth <25316162+hrmacbeth@users.noreply.github.com> Co-authored-by: Rob Lewis <rob.y.lewis@gmail.com>