Expert systems

Unlike neural networks, where a forecast is formed without human involvement, expert systems include one or more highly qualified specialists as an element of the system. An expert system has a branched network that allows queries and deep search in databases and knowledge repositories.

Neural networks operate on the principle of transmitting information from one layer of neurons to another, and the changes in information that occur during transmission are governed by heuristic rules not specified in advance. In expert systems, by contrast, there is a rigid logical framework — a knowledge representation model (KRM) and an inference engine, which automatically conducts the line of reasoning according to the rules embedded in the KRM and uses the parameters involved in the decision. As a result, an expert opinion is produced together with a probabilistic estimate of its reliability. The interface allows several users to work at once, even those who are not specialists in the experts' subject domain.

Expert systems can also be trained. If the answer is known in advance from the assessments of expert specialists, it is compared with the answer produced by the expert system; the rules (and even the KRM) are modified by adding new knowledge, after which the next iteration is carried out.

Expert systems are widely used in business; they often work independently and are not included in corporate information networks. As a rule, they are narrowly specialized in a given subject domain: scientific, transport, medical, banking, trade, legal, and so on.

Examples of decision support systems.

Expert decision support system (ESPPRU. The system is oriented toward automating the procedure of analyzing problem situations and choosing effective decisions. It belongs to the class of information systems combining the advantages of expert systems and decision support systems.

Expert Choice . A commercial software product developed on the basis of the analytic hierarchy process to support decision-making for various organizations. The system has three delivery options: Comparion Core™, Expert Choice 11.5™ and Expert Choice Inside.

Super Decisions*. A software product developed on the basis of the analytic network process (Analytic Network Process).

Decision Lens (Decision Lens Weby. A commercial software product for decision support, having the following methodological features: the theoretical foundations of the system are the analytic hierarchy process and the analytic network process; the presence of a web interface; the possibility of group work.

Imaginatik Idea Central . A commercial system that is a web application for processing expert opinions.

UTA PLUS'. Implements the UTA method, which can be used for solving problems of multi-criteria analysis. The program has a clear graphical interface.

ELECTRE IS . A system from the ELECTRE family, based on a multi-criteria method that allows the use of pseudo-criteria and threshold values in decision-making. In the course of the calculations the system constructs a graph. The sought set of alternatives is the core of this graph.

ELECTRE III-IV [10]. A system implementing a method from the ELECTRE family for criteria that have no relative-importance estimates. The method underlying the system makes it possible to rank alternatives.

ELECTRE TRP. A system implementing a method from the ELECTRE family for solving problems that require segmentation. The segmentation process is based on estimating the internal value of alternatives. The system has a module capable of self-learning on test situations, determining the parameters of the model. It is successfully applied in problems with a large number of alternatives.

IRIS . The system implements the task of sorting alternatives in multi-criteria decision-making problems. It allows the user to set threshold constraints for the criteria. It is able to assess the accuracy of the calculations. It outputs the calculation result in the form of a report.

Imperator 3.1[12] [13] [14]. The program's capabilities make it possible to solve problems of rating, choosing alternatives, allocating resources, forecasting, planning, accounting for preferences, and simulating situations. The system is based on the analytic hierarchy process.

DSS «Expert»1. The system is based on the analytic hierarchy process. Features of the system: support for both numerical values and the user's subjective verbal preferences. The possibility of analyzing data for consistency and reliability, and correcting inconsistency. A convenient graphical interface, tools for formalizing the problem and analyzing results. Detailed printed reports. The presence of a library of standard hierarchies for solving forecasting and management problems in various fields of activity. The presence of a library of solutions to standard problems in the fields of finance, economics, personnel management, enterprise management, and so on.

OPTIMUM . The system is based on the analytic hierarchy process. The possibility of customizing the user interface is implemented. Each user can create a convenient workspace for themselves in this program.

DSS «Choice» 5.3[16]. The system is a simple and convenient tool that helps to structure the problem; build a set of alternatives; identify the factors that characterize them; assign the importance of these factors;

evaluate the alternatives against each of the factors; find inaccuracies and contradictions in the judgments of the DM/expert; rank the alternatives; carry out an analysis of the decision and justify the results obtained.

MRShOShTU[17]. The system is distinguished by a dialog interface adapted to the features of the analytic hierarchy process and to user perception. The dialog tools make it possible to obtain the most complete information about the pairwise comparisons carried out and to eliminate possible inconsistencies in the pairwise comparison matrices. The use of a template mechanism allows the user to adapt the system to their field of activity.

TsUpEKhR+[18]. The system is based on the analytic hierarchy process. Functional capabilities of the system: creating complex and branched hierarchies, calculating the priorities of alternative decisions. Advantages of the system: a user-friendly interface, including interactive help. The possibility of extending the system. The universality of the system with respect to its application in various fields of activity.