tI want to look for some references about Nomizu Conjecture(if $R(X,Y)R = 0$ Then $\nabla R = 0$),is there anyone know some papers/references about Nomizu Conjecture or the progress about Nomizu Conjecture.
1 Answer
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Luis A. Florit, Wolfgang Ziller, Manifolds with conullity at most two as graph manifolds
Abstract states: "... [W]e show that Nomizu's conjecture, well known to be false in general, is true for manifolds with finite volume."