> 20-XX Group theory and generalizations > 20NXX Other generalizations of groups

20N02 Sets with a single binary operation (groupoids)	20N05 Loops, quasigroups	20N10 Ternary systems (heaps, semiheaps, heapoids, etc.)
20N15 $n$-ary systems $(nge 3)$	20N20 Hypergroups	20N25 Fuzzy groups
20N99 None of the above, but in this section

20NXX Other generalizations of groups