[Binghamton Geometry Topology Seminar] This week

[Jonathan Williams]

We had an unexpected cancellation for Thursday, April 26, so if there is 
anyone who would like to speak, please let me know.

On the other hand, there is a joint geometry/topology combinatorics 
seminar on Tuesday:

Speaker: Robert Connelly (Cornell)
Title: Tensegrities: Geometric Structures Suspended in Midair
Time: 1:15 - 2:15
Room: WH-100E

Suppose you have a finite collection of points in Euclidean space or the 
plane. Some pairs are connected by inextendible cables, others by 
incompressible struts, and some by fixed length bars. The artist Kenneth 
Snelson constructed several large structures, made of cables and bars, 
that hold their shape under tension, where the struts appear to be 
suspended in midair. Buckminster Fuller, the architect and inventor, 
called them "tensegrities" because of their "tensional integrity". But 
why do they hold their shape? There is a very simple principle using 
quadratic energy functions that provides the key to their stability. I 
will show a catalog of highly symmetric tensegrities, created with the 
help of a little bit of representation theory, as well as tangible 
models, where you can feel their rigidity first-hand.