Notice of Technical Reports

[Laveen N. KANAL]

What follows is the abstract of a TR printed this summer which has been
subitted for publication. Also included in this message are the titles of two
earlier reports by the sdame authors which were put out in Dec. 1988 but
whic may be of interest now in view of some titles I have seen on the net.

    UMIACS-TR-90-99                                         July 1990
    CS-TR-2508                    

                    ASYMMETRIC MEAN-FIELD NEURAL
                    NETWORKS FOR MULTIPROCESSOR
                              SCHECDULING
                         
                           Benjamin J. Hellstrom
                            Laveen N. Kanal

                           


				Abstract

	Hopfield and Tank's proposed technique for embedding
	optimization problems, such as the travelling salesman, in
	mean-field thermodynamic networks suffers from several
	restrictions. In particular, each discrete optimization problem
	must be reduced to the minimization of a 0-1 Hamiltonian.
	Hopfield and Tank's technique yields fully-connected networks
	of functionally homogeneous visible units with low-order
	symmetric connections. We present a program-constructive
	approach to embedding difficult problems in neural networks.
	Our derivation method overcomes the Hamiltonian reducibility
	requirement and promotes networks with functionally
	heterogeneous hidden units and asymmetric connections of
	both low and high-order. The underlying mechanism involves the
	decomposition of arbitrary problem energy gradients into
	piecewise linear functions which can be modeled as the outputs
	of sets of hidden units. To illustrate our method, we derive
	thermodynamic mean-field neural networks for multiprocessor
	scheduling. The performance of these networks is analyzed by
	observing phase transitions and several improvements are
	suggested. Tuned networks of up to 2400 units are shown to
	yield very good, and often exact solutions.




The earlier reports are

CS-TR-2149  Dec. 1988 by Hellstrom and Kanal, titled " Linear Programming
Approaches to Learning in Thermodynamic Models of Neural Networks"

Cs-TR-2150, Dec. 1988 by Hellstrom and Kanal, titled " Encoding via Meta-Stable
Activation Levels: A Case Study of the 3-1-3 Encoder".

Reports are available free until the current supply lasts after which they
will be available(for a small charge) from the publications group at the
Computer Science Center of the Univ. of Maryland, College Park, Md., 20742.

The address for the current su
supply is : Prof. L.N. Kanal, Dept. of Computer Science, A.V. Williams Bldg,
Univ. ofMaryland, College Park, MD. 20742.

L.K.