2013/07/15 by Tang, Zizhou, Yan, Wenjiao · 1 citation
#Algebraic Topology (math.AT) #Differential Geometry (math.DG) #FOS: Mathematics
paper · doi:10.48550/arxiv.1307.3807
The focal sets of isoparametric hypersurfaces in spheres with g = 4 are all Willmore submanifolds, being minimal but mostly non-Einstein ([TY1], [QTY]). Inspired by A.Gray's view, the present paper shows that, these focal sets are all A- manifolds but rarely Ricci parallel, except possibly for the only unclassified case. As a byproduct, it gives infinitely many simply-connected examples to the problem 16.56 (i) of Besse concerning generalizations of the Einstein condition.