[comp.ai.neural-nets] NN and Bayesian Belief Nets

rupen@csd4.csd.uwm.edu (Rupen Dinesh Sheth) (11/21/89)

I am new in the area of neural nets.  I am trying to compare the neural net
approach to the Bayesian Net approach (by Judea Pearl).

Has anyone worked on this before?  Is it true that single layer neural nets
can perform similar to Bayesian belief networks, and if so has anyone done some
theoretical work on it.

Any pointers and/or suggested readings would be appreciated.
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dhw@itivax.iti.org (David H. West) (11/21/89)

In article <1148@uwm.edu> rupen@csd4.csd.uwm.edu (Rupen Dinesh Sheth) writes:
|I am new in the area of neural nets.  I am trying to compare the neural net
|approach to the Bayesian Net approach (by Judea Pearl).
|
|Has anyone worked on this before?  Is it true that single layer neural nets
|can perform similar to Bayesian belief networks, and if so has anyone done some
|theoretical work on it.

Typical 'neural net' neurons have an internal state that is
characterised by a single scalar, and they perform a scalar
calculation (on which some setups impose the complication of
back-propagation, in which the links have a scalar state).  Pearl's 
nodes must store a multi-dimensional matrix, and transmit vector
messages over their links.

-David West         dhw@itivax.iti.org

hector@maui.cs.ucla.edu (Hector A Geffner) (11/23/89)

In article <4454@itivax.iti.org> dhw@itivax.UUCP (David H. West) writes:
>In article <1148@uwm.edu> rupen@csd4.csd.uwm.edu (Rupen Dinesh Sheth) writes:
>|I am new in the area of neural nets.  I am trying to compare the neural net
>|approach to the Bayesian Net approach (by Judea Pearl).
>|
>|Has anyone worked on this before?  

See "The Probabilistic Semantics of Connectionist Networks", 
     by Geffner and Pearl, in the Proceedings of the First ICNN, San Diego, 
     1987, pp 187-195

>|                             ....  Is it true that single layer neural nets
>|can perform similar to Bayesian belief networks, and if so has anyone done 
>!some theoretical work on it.

Not as far as i know. Representing Bayesian Networks in connectionist 
architectures requires in general higher order connections (eg w_{i,j,k,....}).

>Typical 'neural net' neurons have an internal state that is
>characterised by a single scalar, and they perform a scalar
>calculation (on which some setups impose the complication of
>back-propagation, in which the links have a scalar state).  Pearl's 
>nodes must store a multi-dimensional matrix, and transmit vector
>messages over their links.
>
>-David West         dhw@itivax.iti.org


For Bayesian Networks involving binary (two-valued) variables only, the vector
messages can be reduced to scalars, and the matrix can be expressed in terms
of weights  and thresholds (see ref above).

-hector

billchu@unccvax.UUCP (Tseng Bill Chu) (11/23/89)

Yun Peng and Jim Reggia has implemented several NN Baysian Belief
nets. For detail please send mails to peng@cs.umd.edu or
reggia@cs.umd.edu.

Their scheme will result 99% correctness in finding the correct
baysian hypothesis.
--Bill