Tuesday, October 5, 1999
4:00 PM (reception following)
Room 35-225
LIDS Colloquium
Abstract
Codes described by graphical models are a subject of intense current research interest. Capacity-approaching codes such as turbo codes and low-density parity-check codes are best described as codes on graphs, and their iterative decoding algorithms follow directly from such graphical representations.
This talk presents a general approach to codes on graphs, in which codes are regarded as behavioral systems realized by state representations on a time axis defined by an arbitrary graph. We show that such an approach is quite general, and give many examples. These realizations of systems on unordered time axes may be interesting to system theorists.
Linear or group codes/systems are realized by linear or group graphs. In this case it is possible to define dual graphs such that dual graphs generate dual codes/systems, regardless of the graph topology. This fundamental duality theorem has many corollaries.
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G. David Forney, Jr. has recently retired from Motorola, and is Bernard M. Gordon Adjunct Professor at MIT. He has been teaching 6.451, Principles of Digital Communication, for the past several years. He is the recipient of many awards and honors, including the IEEE Information Theory Society Shannon Medal and the IEEE Edison Medal.
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Modified: Oct 3, 1999|
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