Combining a monad and a comonad

We give a systematic treatment of distributivity for a monad and a comonad as arises in giving category theoretic accounts of operational and denotational semantics, and in giving an intensional denotational semantics. We do this axiomatically, in terms of a monad and a comonad in a 2-category, giving accounts of the Eilenberg–Moore and Kleisli constructions. We analyse the eight possible relationships, deducing that two pairs are isomorphic, but that the other pairs are all distinct. We develop those 2-categorical definitions necessary to support this analysis.     

Optimal distribution of a scarce integer resource on a network of arbitrary topology

We consider optimal allocation of a scarce integer resource to operations in a network technological process. A polynomial-time dynamic programming algorithm is proposed for solving the allocation problem.Translated from Kibernetika, No. 3, pp. 53–61, 81, May–June, 1991.     

A Formal Composition and Interaction Model for a Web Component Platform

A framework for components on the Web needs a formal model that captures essential concepts such as contractual information and service matching. We propose a typed π-calculus-based model for Web components that formalises an extension of the currently discussed Web Services framework. We address in particular activities in the stages of a component life cycle – such as matching, commitment, connection and interaction – that are part of the process that a component is involved in.     

Diffusion approximation for a closed Jackson network

We investigate the asymptotic behavior of a vector queueing process in the Markov model of a closed queueing network. The number of jobs circulating in the network is assumed to increase without bound, while the processing rate at each node is directly proportional to the number of jobs at that node.Translated from Kibernetika, No. 1, pp. 30–33, January–February, 1989.     

NP-completeness of maximum-cut and cycle-covering problems for a planar graph

We consider problems of finding the maximum cut and a cycle covering for a planar graph with edge weights of arbitrary sign. Methods that find the maximum cut in graphs with only positive edge weights are shown to be inapplicable in this case. NP-completeness of the problem is proved.Translated from Kibernetika, No. 1, pp. 13–16, January–February, 1991.     

Necessary condition of optimality in a minimax control problem

We consider the control of bundles of trajectories of linear inclusions. Necessary conditions of extremum are derived in a form that generalizes the Pontryagin maximum principle.Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 117–125, July–August, 1992.     

State-local optimality of a bang–bang trajectory: a Hamiltonian approach

We give a sufficient condition for a bang–bang extremal to be a strong local optimizer for the minimum time problem with fixed endpoints. We underline that the conditions imply that the optimum is local with respect to the state and not necessarily to the final time. Moreover, it is given through a finite-dimensional minimization problem, hence is suited for numerical verification. A geometric interpretation through the projection of the Hamiltonian flow on the state space is also given.     

Estimating the signal acting on a macroscopic body in a controlled potential well

We consider the use of some superconductivity effects for estimating the gravitational signal picked up by a probe in a controlled potential well. Sensitivity in excess of previously attained levels is achieved.Translated from Kibernetika, No. 2, pp. 81–85, March–April, 1989.     

Validating the knowledge base of a production system by the operator coverage criterion

Principles and algorithms are proposed for validating the knowledge base of a production system with the use of the operator coverage criterion. We analyze the complexity of algorithms that verify static correctness and generate test data.Translated from Kibernetika, No. 3, pp. 86–89, May–June 1990.     

Fair Π

In this paper, we define fair computations in the π-calculus [Milner, R., Parrow, J. & Walker, D., A Calculus of Mobile Processes, Part I and II, Information and Computation 100 (1992) 1–78]. We follow Costa and Stirling's approach for CCS-like languages [Costa, G. & Stirling, C., A Fair Calculus of Communicating Systems, Acta Informatica 21 (1984) 417–441, Costa, G. & Stirling, C., Weak and Strong Fairness in CCS, Information and Computation 73 (1987) 207–244] but exploit a more natural labeling method of process actions to filter out unfair process executions. The new labeling allows us to prove all the significant properties of the original one, such as unicity, persistence and disappearance of labels. It also turns out that the labeled π-calculus is a conservative extension of the standard one. We contrast the existing fair testing [Brinksma, E., Rensink, A. & Vogler, W., Fair Testing, Proc. of CONCUR'95, LNCS, 962 (1995) 313–327, Natarajan, V. & Cleaveland, R., Divergence and Fair Testing, Proc. of ICALP '95, LNCS, 944 (1995) 648–659] with those that naturally arise by imposing weak and strong fairness as defined by Costa and Stirling. This comparison provides the expressiveness of the various fair testing-based semantics and emphasizes the discriminating power of the one already proposed in the literature.     

A new colour vision test in a PC-based screening system

The most commonly used method to examine the ability of the visual system to discriminate colours and detect colour vision deficiencies is based on pseudoisochromatic plates, such as the Ishihara plates. We describe a computer-based method to determine red–green colour deficiencies based on an anomaloscope simulator, which gave good results in a study of red–green discrimination is studied. It was shown experimentally that this computer-based method discriminates between subjects with colour deficiencies and subjects without colour deficiencies.     

Estimation of variable regression parameters as a two-criterion problem

We consider parameter estimation for a regression model in which the unknown parameters change between observations.Translated from Kibernetika, No. 3, pp. 67–73, May–June, 1991.     

Constructive description of the effective domain of a dual function

We propose a constructive method of describing the effective domain of a dual function of general form.Translated from Kibernetika, No. 1, pp. 50–54, January–February, 1989.     

Image enhancement using a human visual system model

In this paper we report the result of a set of computer experiments carried out to enhance digital images. We use a special line weight function (LWF) which is a combination of zero- and second-order Hermite functions. We are motivated by the physiological evidence reported in R. A. Young, Spatial Vision 2(4), 273–293 (1987), that visual receptive fields are shaped like the sum of a Gaussian function and its Laplacian. This function can also be derived mathematically when the contrast sensitivity experiments in psychophysics are posed as an eigenvalue problem (A. L. Stewart and R. Pinkham, Biol. Cybernetics 64, 373–379 (1991). Analyses of the edge location error show that the proposed function has extremely good localization capability (i.e. the points marked by the operator is as close as possible to the center of the true edge). We also show that the LWF does not detect phantom edges which do not correspond to significant image intensity changes.     

On the Subsymbolic Nature of a PDP Architecture that Uses a Nonmonotonic Activation Function

PDP networks that use nonmonotonic activation functions often produce hidden unit regularities that permit the internal structure of these networks to be interpreted (Berkeley et al., 1995; McCaughan, 1997; Dawson, 1998). In particular, when the responses of hidden units to a set of patterns are graphed using jittered density plots, these plots organize themselves into a set of discrete stripes or bands. In some cases, each band is associated with a local interpretation. On the basis of these observations, Berkeley (2000) has suggested that these bands are both subsymbolic and symbolic in nature, and has used the analysis of one network to support the claim that there are fewer differences between symbols and subsymbols than one might expect. We suggest below that this conclusion is premature. First, in many cases the local interpretation of each band is difficult to relate to the interpretation of a network's response; a more appropriate relationship only emerges when a band associated with one hidden unit is considered in the context of other bands associated with other hidden units (i.e., interpretations of distributed representations are more useful than interpretations of local representations). Second, the content that a band designates to an external observer (i.e., the interpretation assigned to a band by the researcher) can be quite different from the content that a band designates to the output units of the network itself.. We use two different network simulations – including the one described by Berkeley (2000) – to illustrate these points. We conclude that current evidence involving interpretations of nonmonotonic PDP networks actually illustrates the differences between symbolic and subsymbolic processing.     

Discriminant feature extraction using empirical probability density estimation and a local basis library

The authors previously developed the so-called local discriminant basis (LDB) method for signal and image classification problems. The original LDB method relies on differences in the time–frequency energy distribution of each class: it selects the subspaces where these energy distributions are well separated by some measure such as the Kullback–Leibler divergence. Through our experience and experiments on various datasets, however, we realized that the time–frequency energy distribution is not always the best quantity to analyze for classification. In this paper, we propose to use the discrimination of coordinates based, instead, on empirical probability densities. That is, we estimate the probability density of each class in each coordinate in the wavelet packet/local trigonometric bases after expanding signals into such bases. We then evaluate a power of discrimination of each subspace by selecting the m most discriminant coordinates in terms of the “distance” among the corresponding densities (e.g., by the Kullback–Leibler divergence among the densities). This information is then used for selecting a basis for classification. We will demonstrate the capability of this algorithm using both synthetic and real datasets.     

Minimal trees of a given search number

We consider families of all minimal trees of a given search number, which is an invariant in problems of searching in a graph. The problem of enumeration of these families is solved.Translated from Kibernetika i Sistemnyi Analiz, No. 4, pp. 25–31, July–August, 1992.     

Value of a convex functional

We consider the problem of finding a ball whose mass in a given measure is not less than some fixed value and which minimizes a given convex functional averaged over the ball. A necessary (and in some cases sufficient) condition for an extremal ball is obtained.Translated from Kibernetika i Sistemnyi Analiz, No. 3, pp. 172–175, May–June, 1992.     

Minimizing the location length of a directed graph

We consider the problem of minimizing the location length of a directed acyclic graph with vertices located at integral points. A necessary optimality condition is proved.Translated from Kibernetika i Sistemnyi Analiz, No. 1, pp. 172–175, January–February, 1992.