TITLE: 

  `Threefold transitions in Calabi-Yau models'

The contents of it will be the survey of the papers, 
  1) Morisson-Vafa I, II -- F-theory
  2) Klemm-Mayer-Vafa    -- concrete calculations of 1)
and plus what I have in mind now. Mainly I would like to 
talk(, "ask" mathematicians,) about the cases where 4-cycle 
shrink to zero size presenting some models.

				(Taken from email of S. Hosono)