03E72 2 08A72 2 lower central series 2 17B30 1 17B60 1 20F18 1 20F40 1 20N25 1 Fuzzy group 1 Fuzzy group; fuzzy subgroup; upper central series 1 Lie algebra 1 Lie algebra associated with the lower central series of the group 1 Primary 20N25 1 Sylow p-subgroup 1 ascendant fuzzy subgroup 1 characteristic function 1 fuzzy subgroup 1 nilpotent fuzzy group 1 nilpotent fuzzy group; support subgroup; characteristic function 1 normalizer condition 1 semidirect product 1 symmetric group 1 wreath product 1