Homogeneity degree of fans

Abstract

The homogeneity degree of a topological space $X$ is the number of orbits of the action of the homeomorphism group of $X$ on $X$. We initiate a study of dendroids of small homogeneity degree, beginning with fans. We classify all smooth fans of homogeneity degree $3$, and discuss non-smooth fans and prove some results on degree $4$