Exotic Differential Structures in Dimension 2
  It is known that the long line supports $2^{\aleph_1}$ many non-diffeomorphic differential structures. We show that the long plane supports a similar number of exotic differential structures, ie structures which are not merely diffeomorphic to the product of two structures on the factor spaces. 
Sunanda Dikshit and David Gauld
math.GN math.GT