Showing papers on "Decision tree model published in 1985"

Distributed Sorting

Abstract: The problem of sorting a file distributed over a number of sites of a communication network is examined. Two versions of this problem are investigated; distributed solution algorithms are presented; and their communication complexity analyzed both in the worst and in the average case. The worst case bounds are shown to be sharp, with respect to order of magnitude, for large files.

Applications of Ramsey's theorem to decision tree complexity

Abstract: Combinatorial techniques for extending lower bound results for decision trees to general types of queries are presented. Problems that are defined by simple inequalities between inputs, called order invariant problems, are considered. A decision tree is called k-bounded if each query depends on at most k variables. No further assumptions on the type of queries are made. It is proved that one can replace the queries of any k-bounded decision tree that solves an order-invariant problem over a large enough input domain with k-bounded queries whose outcome depends only on the relative order of the inputs. As a consequence, all existing lower bounds for comparison-based algorithms are valid for general k-bounded decision trees, where k is a constant.An O(n log n) lower bound for the element uniqueness problem and several other problems for any k-bounded decision tree, such that k = O(nc) and c

A model of computation for VLSI with related complexity results

Abstract: A new model of computation for VLSI, based on the assumption that time for propagating information is at least linear in the distance, is proposed. While accommodating for basic laws of physics, the model is designed to be general and technology independent. Thus, from a complexity viewpoint, it is especially suited for deriving lower bounds and trade-offs. New results for a number of problems, including fan-in, transitive functions, matrix multiplication, and sorting are presented. As regards upper bounds, it must be noted that, because of communication costs, the model clearly favors regular and pipelined architectures (e.g., systolic arrays).

Lower bounds in algebraic computational complexity

Abstract: The present article is a survey of selected methods for obtaining lower bounds in algebraic complexity. We present the contents. Introduction. i. Basic concepts. Chapter I. Algebraic-geometric approach to obtaining lower bounds of computational complexity of polynomials. 2. Evaluating a polynomial with "general" coefficients. 3. Computational complexity of individual polynomials. 4. The degree method and its generalizations (the case of an infinite ground field). 5. The degree method (the case of a finite ground field). 6. Additive complexity and real roots. Chapter II. Lower bounds on multiplicative complexity for problems of linear algebra. 7. Multiplicative complexity and rank. 8. Rank of a pair of bilinear forms. 9. Multiplicative complexity of a bilinear form over a commutative ring. i0. Bounds on the rank of algebras, ii. Linearized multiplicative complexity. Chapter III. Complexity for straight-line programs of nonstandard types. 12. Irrational computational complexity of algebraic functions. 13. Monotone programs. 14. Time-space tradeoffs. 15. Graph-theoretic methods in algebraic complexity. 16. Additive complexity in triangular and directed computations and Bruhat decomposition.

An Application of Computerized Decision Tree Models in Management-Union Bargaining

Abstract: The labor contract bargaining environment poses major challenges to the team bargaining with the union. A computerized decision tree model helped one team to develop reasonable bargaining positions that were acceptable to both management and the union. By graphically describing the gains and risks associated with alternative positions, the model enhanced communication within the team and with management.

Using the Decision-Tree Model in Database Design

Abstract: In database design, the logical, or end user, view of data is often different from the physical view. In the last decade, researchers and designers have made considerable effort to represent additional views of data between these two extremes.' 2 An effort such as this requires that designers consider the type of system on which the database would be implemented, data manipulations, retrieval language, consistency, and integrity. It is also desirable to design databases with good consistency checks, minimized data redundancy, and data migration control. Existing systems are essentially relational, hierarchical, or network models. Examples of a relational model are Relational Software's Oracle and IBM's System R,3 which uses the Sequel language for data definition, control, and manipulation. IBM's IMS and Adabas by Software AG are examples of the hierarchical model, the latter using the Associators (a set of inverted lists of Internal Sequence numbers, or ISNs). Honeywell's IDS and Univac's DMS-1100 fall into the network model category. The decision-tree model presented here is based on several months of research. It is partly an extension of the database design effort of a dental information system for the clinical amalgam restoration of patients4 and a dental information system model for the logical design of a centralized database.5 Figure 1 gives a conceptual overview of the D-T model. The decision-tree model is being used at Multnomah County Data Processing Authority in the design of a Problem and Change Tracking Directory System, or PCTDS, and an Incident Tracking System, or ITS, database for the Department of Public Safety, Multnomah County, Oregon. PCTDS's target system is Adabas* while ITS is being implemented on Oraclet with Sequel as the query language. The work in both dental information systems,4'5 was implemented on a test basis on Adabas. Simple transformations were made in the logical views to reflect attribute types and record types, which form fields and subrecords, respectively, in an Adabase file system. With this decision-tree model, programmers can easily understand the entire system from the enterprise view to the physical design level, depending on the subsequent approach of the designer. In addition, they can quickly identify their areas of interest