Title:  Amenable L2-signatures and cobordism of knots and 3-manifolds

Abstract: Recently, new amenable Cheeger-Gromov rho-invariants have been 
introduced to study homology cobordism of 3-manifolds and concordance of 
knots and links.  This reveals new structures beyond those visible via 
Cochran-Orr-Teichner type signatures.  We introduce the key ideas of 
amenable L2 methods and some applications.  Also, if time permits, we 
discuss the notion of symmetric Whitney tower cobordism which provides a 
generalized framework for bordered 3-manifolds and link concordance.  
Parts of the results in this talk are joint with Kent Orr.