  Let X be an n-dimensional Calabi-Yau with ordinary double points, where n is
odd. Friedman showed that for n=3 the existence of a smoothing of X implies a
specific type of relation between homology classes on a resolution of X. (The
converse is also true, due to work of Friedman, Kawamata and Tian.)
  We sketch a more topological proof of this result, and then extend it to
higher dimensions. For n>3 the "Yukawa product" on the middle dimensional
(co)homology plays an unexpected role. We also discuss a converse, proving it
for nodal Calabi-Yau hypersurfaces in projective space.
