2.00-3.00 p.m., Lecture Hall 2
Automorphisms of the Rational World
Chennai Mathematical Institute.
A theorem of Sierpinski shows that any countable metric space with no isolated points is homeomorphic to the rational numbers Q. In light of this fact, Peter Neumann coined the term "Rational World" to describe all such spaces. Following Neumann's paper 'Automorphisms of the Rational World', we use Sierpinski's theorem to investigate the homeomorphisms from Q to itself, and characterize all possible automorphisms of Q in terms of their cycle decompositions.