New tech report

[Subutai Ahmad]

The following technical report is available:

       A Network for Extracting the Locations of Point Clusters
		      Using Selective Attention

				by

		  Subutai Ahmad & Stephen Omohundro
	       International Computer Science Institute

		    ICSI Technical Report #90-011

			       Abstract

This  report explores  the problem   of  dynamically computing  visual
relations in connectionist systems.   It  concentrates  on the task of
learning whether three  clumps of points  in a 256x256   image form an
equilateral triangle. We argue that  feed-forward networks for solving
this task would not scale well to images of this size. One  reason for
this is that local information does not contribute to the solution: it
is necessary to  compute relational information  such as the distances
between points. Our solution  implements  a mechanism for  dynamically
extracting the locations of the   point clusters. It  consists  of  an
efficient focus of attention mechanism and a cluster detection scheme.
The   focus of attention  mechanism allows   the system  to select any
circular portion  of the image in  constant time. The cluster detector
directs the  focus of attention  to  clusters in the image. These  two
mechanisms are used  to sequentially extract the relevant coordinates.
With  this  new representation  (locations   of  the  points) very few
training  examples  are required  to learn the  correct  function. The
resulting network is also very compact: the number of required weights
is proportional to the number of input pixels.


Copies can be obtained in one of two ways:

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file is ahmad.tr90-11.ps.Z in the pub/neuroprose directory. You can
either use the Getps script or follow these steps:

unix:2> ftp cheops.cis.ohio-state.edu
Connected to cheops.cis.ohio-state.edu.
Name (cheops.cis.ohio-state.edu:): anonymous
331 Guest login ok, send ident as password.
Password: neuron
230 Guest login ok, access restrictions apply.
ftp> cd pub/neuroprose
ftp> binary
ftp> get ahmad.tr90-11.ps.Z
ftp> quit
unix:4> uncompress ahmad.tr90-11.ps.Z 
unix:5> lpr ahmad.tr90-11.ps


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--Subutai Ahmad
ahmad at icsi.berkeley.edu