From: samodena@csemail.cropsci.ncsu.edu (S. A. Modena)
Subject: VSLI Spatial Entropy Measure
Summary: Practical application of the entropy concept
Keywords: entropy
Organization: Crop Science Dept., NCSU, Raleigh, NC 27695-7620
Date: Fri, 9 Oct 1992 23:32:17 GMT

The relayed item below is self-explanatory.  I think it is
closer to Shannon's mode of thinking about entropy being a 
descriptive attribute of a (dynamic) communications systems.
At least, this is a move away from the current abstract conjectures
on pseudo-worlds of no relavence to designing biological molecular
communications systems.

    ----------------Cut Here------------------
>Newsgroups: general,triangle.talks
>Subject: Doctoral Dissertation Defense - Suresh Rajgopal
>Message-ID: <16171@borg.cs.unc.edu>
>Date: 7 Oct 92 17:07:27 GMT


         The University of North Carolina at Chapel Hill
                 Department of Computer Science                  

                  Doctoral Dissertation Defense

                         Suresh Rajgopal

                   Wednesday, October 14, 1992
                             1:00 pm
                  014 Classroom, Sitterson Hall
   Refreshments will be served afterwards in the lower lobby of Sitterson

             Spatial Entropy- A Unified Attribute to Model
                Dynamic Communication in VLSI Circuits


Improvement in fabrication and processing technology has raised the level 
of integration in VLSI circuits to over a million transistors on chip. 
While scaling device dimensions has yielded smaller and faster transistors 
and gates, the higher density has made it more difficult to connect these 
devices.  Moreover, the cost of wiring and interconnect can no longer be 
neglected;  the circuit (area-time and power) performance is being 
increasingly dominated  by the communication between the logic gates  
rather than the  gates themselves. This dissertation addresses the problem 
of capturing the cost of this communication.

The Computer-Aided-Design tools used by a designer often rely on information  
provided by various circuit attributes, where the quality of the solutions 
are frequently dictated by the kind and the amount of information provided 
by these attributes. For instance a static circuit attribute can capture 
circuit structure, but it fails to capture dynamic usage and its distribution 
over the various parts of the circuit.  The contribution of this  research 
is a new circuit attribute called spatial entropy.  It models the dynamic 
communication effort in the circuit by unifying the static structure and 
the dynamic movement of data in the circuit.

The dissertation introduces the concept of spatial entropy to the VLSI CAD 
domain, in the form of a quantative circuit attribute.  This is used to 
describe a simple and efficient procedure to compute spatial entropy for 
primitive gates and for an entire circuit.  We characterize the attribute 
comprehensively over different  levels of abstraction, and extend our 
definition to describe spatial  entropy vectors. Finally, we illustrate 
applications of spatial entropy in  two problems in CAD - variable ordering 
for binary decision diagrams (BDD),  and boolean function complexity, to 
demonstrate its  ability to  capture fundamental  function behavior over 
a broad class of implementations.

HOST:  	Professor Kye Hedlund, 962-1756, hedlund@cs.unc.edu

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