Boltzmann machines and their applications

In this paper we present a formal model of the Boltzmann machine and a discussion of two different applications of the model, viz. (i) solving combinatorial optimization problems and (ii) carrying out learning tasks. Numerical results of computer simulations are presented to demonstrate the characteristic features of the Boltzmann machine

Boltzmann machines for travelling salesman problems

Boltzmann machines are proposed as a massively parallel alternative to the (sequential) simulated annealing algorithm. Our approach is tailored to the travelling salesman problem, but it can also be applied to a more general class of combinatorial optimization problems. For two distinct 0–1 programming formulations of the travelling salesman problem (as a linear and as a quadratic assignment problem) it is shown that near-optimal solutions can be obtained by mapping the corresponding 0–1 variables onto the logic computing elements of a Boltzmann machine, and by transforming the cost functions corresponding to the 0–1 programming formulations into the consensus function associated with the Boltzmann machine. Results of computer simulations are presented for two problem instances, i.e. with 10 cities and 30 cities, respectively

Improving disk efficiency in video servers by random redundant storage

Random redundant storage strategies have proven to be an interesting solution for the problem of storing data in a video server. Several papers describe how a good load bal ance is obtained by using the freedom of choice for the data blocks that are stored more than once. We improve on these results by exploiting the multi-zone character of hard disks. In our model of the load balancing problem we incorporate the actual transfer times of the blocks, depending on the zones in which the blocks are stored. We give an MILP model of the load balancing problem which we use to de rive a number of good load balancing algorithms. We show that, by using these algorithms, the amount of data that is read from the fast zones is substantially larger than with conventional strategies, such that the disks are used more efficiently

Simulated annealing

\u3cp\u3eMany problems in engineering, planning and manufacturing can be modeled as that of minimizing or maximizing a cost function over a finite set of discrete variables. This class of so-called combinatorial optimization problems has received much attention over the years and major achievements have been made in its analysis (Ausiello et al.\u3c/p\u3

Ontology-based information extraction from the world wide web

\u3cp\u3eWe study possibilities to automatically extract information from the Internet, by structuring and combining data from web pages. The web pages are found with the use of a search engine and the information is structured by using ontologies. The ontologies are populated with the use of statistical and linguistic techniques. We present the results of a case study that is aimed at finding the names of famous persons. The results indicate that, even if we only use the summaries that Google provides of web pages, the approach results in a high precision and recall for the specific application.\u3c/p\u3

Methods to optimally trade bandwidth against buffer size for a VBR stream

To reduce the peak bit-rate for transmitting a variable-bit-rate stream, one can prefetch and buffer data at the receiving side. Previous work shows how to minimize the required buffer size given the available bandwidth [Feng, 19971 and how to minimize the required bandwidth given the available buffer size [Salehi et al., 1998]. Instead of taking either bandwidth or buffer size fixed, we as sume both to be decision variables with given cost coefficients. We explain our method [Den Boef et al., 2003a] and the method by Chang et al. [1998] and compare them. These methods find the optimal values by starting with a minimum value for either the bandwidth [Chang et al., 19981 or the buffer size [Den Boef et al., 2003a] and then increasing this value, while at the same time decreasing the value of the buffer size or the bandwidth, respectively. We conclude that our method has slightly better run times than the method by Chang et al. and uses about half the amount of memory