Jean-François Lafont

EZ-structures and topological applications

In this paper, we introduce the notion of an EZ-structure on a group, an equivariant version of the Z-structures introduced by Bestvina [4]. Examples of groups having an EZ-structure include (1) torsion free

Blocking light in compact Riemannian manifolds

\delta

Lower algebraic K-theory of hyperbolic 3-simplex reflection groups

-hyperbolic groups, and (2) torsion free

Relating the Farrell Nil-groups to the Waldhausen Nil-groups

CAT(0)

Lower algebraic K-theory of certain reflection groups

-groups. Our first theorem shows that any group having an EZ-structure has an action by homeomorphisms on some

4-dimensional locally CAT(0)-manifolds with no Riemannian smoothings

(\mD^n, \Delta)

Splitting formulas for certain Waldhausen Nil-groups

, where

Algebraic K-theory of virtually free groups

n

Aspherical manifolds that cannot be triangulated

is sufficiently large, and

Marked length rigidity for one-dimensional spaces

\Delta