Problem of the Week
BUGCAT
Zassenhaus Conference
Hilton Memorial Lecture
BingAWM
Math Club
A hypergroup is stringent if a ⊞ b is a singleton whenever a ≠ b. A hyperfield is stringent if the underlying additive hypergroup is. Every doubly distributive skew hyperfield is stringent, but not vice versa. I present a classification of stringent hypergroups, from which a classification of doubly distributive skew hyperfields follows.