Almgren and topological minimality for the set $Y\times Y$
  In this paper we discuss various minimality properties for the orthogonal product of two 1-dimensional $\Y$ sets, and some related problems. This is motivated by an attempt to give the classification of singularities for 2-dimensional Almgren-minimal sets in $\R^4$. 
Xiangyu Liang
math.CA math.DG math.FA