[Colloquium] Reminder: Talks Today at TTI-C: McAllester & Jansson (4/19)

[Katherine Cumming]

Show and Tell  Series
Speaker:  David McAllester, TTI-C
Speaker's Homepage:  http://www.tti-c.org//mcallester.html
 
Time:  Tuesday, April 19th @ 12:15pm - Lunch Provided by TTI-C
Place:  TTI-C Conference Room
Title:  A* beats Dynamic Programming
Abstract:
This talk will describe a generalization of A* search to a wide class of
dynamic programming optimization algorithms. A dynamic programming
optimization algorithm is defined in general as a set of rules for
deriving table entries from table entries. This general definition can
be made precise using concepts from bottom-up logic programming. We show
that for any dynamic programing algorithm in this class there is also a
Dijkstra lightest derivation algorithm and an A* algorithm. We also show
that, in general, admissible A* heuristics can be constructed in a
mechanical way from abstraction functions on the assertion set (set of
possible table entries). Hierarchies of abstractions can be constructed
where each level of the hierarchy provides a heuristic for computing the
level below. All levels of the abstraction hierarchy can be computed
simultaneously on a single priority queue. These algorithmic
observations lead to an "AI architecture" for the "perception pipeline"
with a particular algorithm for allowing high level (or late) abstract
processing to guide low level concrete processing. Applications in
language and vision will be discussed.

This is joint work with Pedro Felzenszwalb. 
 
Guest Speaker 
 
Speaker:  Johan Jansson, Chalmers University of Technology
Speaker's Homepage:  http://www.math.chalmers.se/~johanjan/
 
Time:  Tuesday, April 19th, 2005 @ 3:00pm
Place:  TTI-C Conference Room
Title:  Solving an Elasto-Plastic Model Using DOLFIN
Abstract:
We discuss a model of elasto-plasticity supporting large displacements
based on an updated Lagrangian formulation. The model is discretized
using the finite element method. The computation is done in the FEniCS
framework, which is a collection of free software components for finite
element computation. We describe how the computation is carried out,
mainly using the DOLFIN component, which is a C++ interface to FEniCS.
We also show new developments in FEniCS, where the FEniCS Form Compiler
(FFC) is used to pre-compute much of the assembly work previously done
in DOLFIN, leading to a large speed increase in assembly. 
 
If you have questions, or would like to meet the speaker, please contact
Katherine at 773-834-1994 or kcumming at tti-c.org. For information on
future TTI-C talks or events, please go to the TTI-C Events
<http://ttic.uchicago.edu/events/events_dyn.php>  page. 
 
 
 
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