1200 E California Blvd | Pasadena, CA 91125

Tel: (626) 395-4335 | Fax: (626) 585-1728

Caltech

2:00 - 6:00 pm

Sloan room 151

3:15-4:15 Garrett Ervin (UCI)

4:15-5:00 Coffee Break

5:00-6:00 Siddharth Bhaskar (UCLA)

Return to top

space of measure-preserving actions of a countable group modulo weak

equivalence. We will define a natural Polish topology on this space and

address the questions of how to represent its convex structure as induced

from a Banach space and whether this structure forms a Poulsen simplex. We

will also introduce a stronger (nonseparable) topology in which it forms a

topological semigroup.

linear order that is isomorphic to its lexicographic cube but not

isomorphic to its square. The analogous question has been answered for

various other kinds of structures: it is known that there are groups that

are isomorphic to their cube but not to their square (even countable

ones), and similarly for modules, Boolean algebras, and Banach spaces. In

this talk, I will show that if such a linear order exists, it is

necessarily uncountable. I will also give a general characterization of

structures X satisfying equations of the form A x X = X, and show how this

can be used to construct structures that are isomorphic to their n-th

power, for any n.

first-order structures. We may allow functions given by arbitrary

recursive definitions, or we may restrict ourselves to “iterative”

functions computable by nothing more complicated than while loops.

In the classical case of recursion over the natural numbers, these two

notions of computability coincide. However, this is not true in

general. We ask whether there is a model-theoretic classification of

structures over which iteration is as powerful as recursion.

In this talk I will discuss some conditions which affect this outcome

one way or the other. I will also give a few examples of

“intermediate” structures for which the question of recursion vs.

iteration reduces to hard open problems in computational complexity.

Return to top

View Larger Map |
Address: 1200 E. California Blvd. Pasadena, CA 91125 Take a look at the Caltech campus map There is free Saturday parking in underground structure #126.
Feel free to park in any of the commuter spaces (these are
marked by a red line). Talks will be held in Sloan building #37, Room 151
on the ground floor |

Return to top

Itay Neeman (UCLA). Organizer Information

Matthew Foreman (UCI). Organizer Information

Martin Zeman (UCI) Organizer Information

Andrew Marks (Caltech) Organizer Information

Jay Williams (Caltech) Organizer Information

Return to top

Earlier Meetings