---------------------------------------------------------------------------
`Quotients of the conifold in compact Calabi-Yau threefolds'

Abstract: I will explain why multiply-connected Calabi-Yau manifolds are 
important for heterotic string compactifications, and go on to describe a 
class of singularities which arise generically in such spaces. In fact 
these are quotients of the well-known conifold geometry. Toric geometry can 
be used to resolve these singularities, realising a new type of topological 
transition between compact Calabi-Yau manifolds. These results therefore 
provide explicit embeddings of an interesting class of singularities in 
compact threefolds, as well as a new technique for constructing compact 
Calabi-Yau manifolds.
---------------------------------------------------------------------------