2021.01.13 14:18:03 (1349344961490112515) from Daniel J. Bernstein:
Digression into computational geometry: The Freeman--Millman--Snoeyink integer-hull algorithm https://web.archive.org/web/20170705095627/https://www.cs.bgu.ac.il/~eurocg14/papers/paper_58.pdf does not work correctly. For example, input (-4,2), (5/2,-1), (-2,5) fails to include (-2,5) in output; the algorithm makes wrong decisions after finding (1,1).