Presented by: 
Peter Cameron (University of St Andrews and Queen Mary University)
Mon 7 Dec, 2:00 pm - 3:00 pm
Prentice Building (42), room 115

I will talk about some aspects of four remarkable objects: the countable random graph (or Rado graph), the rational numbers (as ordered set), the Urysohn metric space, and the pseudo-arc. These objects appear in many different areas of mathematics, but they have certain features in common: they can be constructed as suitable limits of finite combinatorial structures; many of their properties can be investigated by combinatorial techniques; and they provide mechanisms for some very interesting interactions between combinatorics and other parts of mathematics (for example, the KPT theorem connecting Ramsey theory with topological dynamics).