120648016
Theory of convex cones in multicriteria decision making
We develop the theory of convex polyhedral cones in the objective-function space of a multicriteria decision problem. The convex cones are obtained from the decision-maker's pairwise judgments of decision alternatives and are applicable to any quasiconcave utility function. Therefore, the cones can be used in any progressively articulated solution procedure that employs pairwise comparisons. The cones represent convex sets of solutions that are inferior to known solutions to a multicriteria problem. Therefore, these convex sets can be eliminated from consideration while solving the problem. We develop the underlying theory and a framework for representing knowledge about the decision-maker's preference structure using convex cones. This framework can be adopted in the interactive solution of any multicriteria problem after taking into account the characteristics of the problem and the solution procedure. Our computational experience with different multicriteria problems shows that this approach is both viable and efficient in solving practical problems of moderate size.
13648716
EARS: An online bibliographic search and retrieval system based on ordered explosion
Abstract Ergonomics Abstracts Retrieval System (EARS) is an online bibliographic information search and retrieval system using the hierarchical subject classification of the Ergonomics Abstracts . EARS is designed using an inverted file organization and is implemented on CDC-Cyber. The data base of abstracts is organized using a fixed-length record format, where each logical record corresponds to a variable number of fixed-length physical records. Accordingly, an index for the identification of physical records from the logical records is used. The data base is inverted on a three-level hierarchical classification scheme and postings files are used for data base inversion. The data base is accessed after selectively traversing a 4-layer structure of indexes and postings files. EARS provides facilities to perform combinations of searches, limited searches, and certain editing functions. The system is currently used extensively by the Western New York Human Factors research community. The logical and physical designs of EARS, its interactive operational features, and its current expansions are described in this paper.
6732453
Enterprise computing environments and cost assessment
5067407
An integrated framework for decision support in corporate planning
Abstract Corporate planning and decision making is a complex but critical management process in multidivisional organizations. This process entails a determination of the objectives and operational constraints at various levels of management. The decision-making function in such large diversified corporations proceeds by assessing the decision alternatives at each level of management with reference to their mutual tradeoffs, and arriving at an equilibrium point. In this paper, we develop a conceptual framework for the design of an integrated DSS in hierarchical organizations. The proposed framework consists of five steps: Analysis of the corporate decision making process, building a model of the decision making process, configuring a DSS for this model, pilot study and implementation. We illustrate the proposed design principles by considering a three-level hierarchical organization and modeling the decision-making process within this organization. A case analysis of the proposed integrated framework is provided. The case study has been conducted with decision makers in a simulated business environment. This research has given rise to several new avenues of exploration and extensions of the proposed design. We present the conclusions from this study and directions for future research in this area. Our experience with this approach in the case analysis has been quite positive, and this suggests that similar results may be obtained in real world organizations as well. We are currently testing the proposed approach with a local organization.
32066139
Topographically discounted Internet infrastructure resources: a panel study and econometric analysis
The Internet infrastructure is increasingly utilized for the provision and delivery of a variety of services. The rapid growth and substantial demand fluctuations of the supported services are placing strain on the service providers to effectively manage their infrastructure resources. Capacity Provision Network (CPN) is a market-driven mechanism that enables the service providers to efficiently allocate, share and trade service capabilities. Central to the operation of CPN is the notion of discounted capacities which capture the underlying topology of the Internet. It serves as a practical instrument for service providers to evaluate the utility of capacity services available at remote sites vis-à-vis the capacities available locally and from the content providers. We conducted an Internet based longitudinal field experiment to empirically assess and validate the critical properties of discount factors. Our analysis reveals that discount factors exhibit markedly lower volatility than network delays, and are more stable over seasonal and temporal trend patterns. The results related to size effects suggest that sharing and trade agreements with larger content can be particularly effective. Our finding on the existence of the concavity property points to the ability of intermediation services to enhance the overall gains from resource sharing arrangements.
120676923
Preference Structure Representation Using Convex Cones in Multicriteria Integer Programming
A new efficient system of representing the decision-maker's preference structure in solving multicriteria integer programming problems is developed. The problem is solved by an interactive branch-and-bound method that employs the procedure of Zionts and Wallenius Zionts, S., J. Wallenius. 1983. An interactive multiple objective linear programming method for a class of underlying nonlinear utility functions. Management Sci.295. for multicriteria linear programming. The decision-maker's underlying utility function is assumed to be pseudoconcave, and his pairwise comparisons of decision alternatives are used to determine his preference structure in terms of certain convex cones in the objective function space and constraints on the weights on the objectives in the weight space. The two forms of preference structure representation are interrelated, and their underlying theory is developed. The primary objective of a representation scheme is exactness, and, in this respect, it is shown that the constraints on the weights are not adequate for representing nonlinear utility functions. On the other hand, the convex cones exactly represent any quasiconcave utility function and clearly avoid the approximations and inaccuracies in other utility assessment systems. Accordingly, an efficient ordered representation using convex cones is developed. An algorithmic framework for multicriteria integer programming that integrates the representation using convex cones with the branch-and-bound solution procedure is developed. Computational experience with bicriteria problems having up to 80 variables and 40 constraints is presented.
46697244
Multistage Indexing for Speeding Prolog Executions
In a previous article we proposed a new and efficient indexing technique that utilizes all the functors in the clause-heads and the goal. The salient feature of this technique is that the selected clause-head unifies (modulo nonlinearity) with the goal. As a consequence, our technique results in sharper discrimination, fewer choice points and reduced backtracking. 
 
 
 
A naive and direct implementation of our indexing algorithms considerably slowed down the execution speeds of a wide range of programs typically seen in practice. This is because it handled deep and shallow terms, terms with few indexable arguments, small and large procedures uniformly. To beneficially extend the applicability of our algorithms we need mechanisms that are ‘sensitive’ to term structures and size and complexity of procedures. We accomplish this in the v-ALS compiler by carefully decomposing our indexing process into multiple stages. The operations performed by these stages increase in complexity ranging from first argument indexing to unification (modulo nonlinearity). Further the indexing process can be terminated at any stage if it is not beneficial to continue further. 
 
 
 
We have now completed the design and implementation of v-ALS. Using it we have enhanced the performance of a broad range of programs typically encountered in practice. Our experience strongly suggests that indexing based on unification (modulo nonlinearity) is a viable idea in practice and that a broad spectrum of useful programs can realize all of its benefits.
10316561
Variable-depth trie index optimization: theory and experimental results
We develop an efficient approach to Trie index optimization. A Trie is a data structure used to index a file having a set of attributes as record identifiers. In the proposed methodology, a file is horizontally partitioned into subsets of records using a Trie index whose depth of indexing is allowed to vary. The retrieval of a record from the file proceeds by “stepping through” the index to identify a subset of records in the file in which a binary search is performed. This paper develops a taxonomy of optimization problems underlying variable-depth Trie index construction. All these problems are solvable in polynomial time, and their characteristics are studied. Exact algorithms and heuristics for their solution are presented. The algorithms are employed in CRES-an expert system for editing written narrative material, developed for the Department of the Navy. CRES uses several large-to-very-large dictionary files for which Trie indexes are constructed using these algorithms. Computational experience with CRES shows that search and retrieval using variable-depth Trie indexes can be as much as six times faster than pure binary search. The space requirements of the Tries are reasonable. The results show that the variable-depth Tries constructed according to the proposed algorithms are viable and efficient for indexing large-to-very-large files by attributes in practical applications.
46377078
A Portable Method of Integrating SLG Resolution into Prolog Systems
1912830
Automata-driven efficient subterm unification
Syntactic unification has widespread use in computing. There are several operations used in deductive computing such as critical pair generation, paramodulation and narrowing that require unifying a term s with every subterm of another term p. This subterm unification problem can be solved naively by repeatedly unifying s with each subterm of p in isolation. The drawback of doing unification in isolation is that commonality among subterms of p is ignored. We present an algorithm for efficient subterm unification by exploiting this commonality. The central idea used in our algorithm is to reduce the common part computation in unification into a string-matching problem and solve it efficiently using a string-matching automaton. The automaton succinctly captures the commonality between subterms of p. The string-matching approach, in conjunction with two new techniques called bidirectional-reduce and marking enables efficient unification of s with every subterm of p.
6173091
Automata-driven indexing of Prolog clauses
Indexing Prolog clauses is an important optimization step that reduces the number of clauses on which unification will be performed and can avoid the pushing of a choice point. It is quite desirable to increase the number of functors used in indexing as this can considerably reduce the size of the filtered set. However this can cause an enormous increase in running time if indexing is done naively. This paper describes a new technique for indexing that utilizes all the functors in a clause-head. More importantly, in spite of using all the functors, this technique is still able to quickly select relevant clause-heads at run time. This is made possible primarily by a finite-state automaton that guides the indexing process. The automaton is constructed at compile time by preprocessing all the clause-heads.