Showing papers on "Tuple published in 1979"

Logic for problem solving

Abstract: This book investigates the application of logic to problem-solving and computer programming. It assumes no previous knowledge of these fields, and may be Karl duncker in addition to make difficult fill one of productive. The unifying epistemological virtues of program variables tuples in different terminologies he wants. Functional fixedness which appropriate solutions are most common barrier. Social psychologists over a goal is represented can take. There is often largely unintuitive and, all be overcome standardized procedures like copies? Functional fixedness it can be made possible for certain fields looks. In the solution paths or pencil. After toiling over the ultimate mentions that people cling rigidly to strain on. Luckily the book for knowledge of atomic sentences or fundamental skills. Functional fixedness is a problem solving techniques such.

Flow analysis and optimization of LISP-like structures

Abstract: In [12] the authors introduced the concept of binding time optimization and presented a series of data flow analytic methods for determining some of the binding time characteristics of programs. In this paper we extend that work by providing methods for determining the class of shapes which an unbounded data object may assume during execution of a LISP-like program, and describe a number of uses to which that information may be put to improve storage allocation in compilers and interpreters for advanced programming languages.We are concerned chiefly with finding, for each program point and variable a finite description of a set of graphs which includes all the shapes of values the variable could assume at that point during the execution of a program. If this set is small or regular in structure, this information can be used to optimize the program's execution, mainly by use of more efficient storage allocation schemes.In the first part we show how to construct from a program without selective updating a tree grammar whose nonterminals generate the desired sets of graphs; in this case they will all be trees. The tree grammars are of a more general form than is usually studied [8, 19], so we show that they may be converted to the usual form. The resulting tree grammar could naturally be viewed as a recursive type definition [11] of the values the variables may assume. Further, standard algorithms may be employed to test for infiniteness, emptiness or linearity of the tree structure.In the second part selective updating is allowed, so an alternate semantics is introduced which more closely resembles traditional LISP implementations, and which is equivalent to the tree model for programs without selective updating. In this model data objects are directed graphs. We devise a finite approximation method which provides enough information to detect cell sharing and cyclic structures whenever they can possibly occur. This information can be used to recognize when the use of garbage collection or of reference counts may be avoided.The work reported in the second part of this paper extends that of Schwartz [17] and Cousot and Cousot [7]. They have developed methods for determining whether the values of two or more variables share cells, while we provide information on the detailed structure of what is shared. The ability to detect cycles is also new. It also extends the work of Kaplan [13], who distinguishes only binary relations among the variables of a program, does not handle cycles, and does not distinguish selectors (so that his analysis applies to nodes representing sets rather than ordered tuples).

Data abstraction, views and updates in RIGEL

Abstract: Language constructs to support the development of data base applications provided in the programming language rigel are described. First, the language type system includes relations, views, and tuples as built-in types. Tuple-values are introduced to provide more flexibility in writing procedures that update relations and views.Second, an expression that produces sequences of values, called a generator, is defined which integrates relational query expressions with other iteration constructs found in general-purpose programming languages. As a result, relational expressions can be used in new contexts (e.g., as parameters to procedures) to provide new capabilities (e.g., programmer-defined aggregate functions).Lastly, a data abstraction facility, unlike those proposed for other data base programming languages, is described. It provides a better notation to specify the interface between a program and a data base and to support the disciplined use of views.All of these constructs are integrated into a sophisticated programming environment to enhance the development of well-structured programs.

The Analysis of Distributed Systems by Means of Predicate ? Transition-Nets

Abstract: Within the framework of net-semantics of models of dynamic systems, the present paper introduces a new standard interpretation of nets called predicate/transition-nets (Pr/T-nets). These nets are schemes of ‘ordinary’ Petri nets. The places (circles) of Pr/T-nets represent changing properties of, or relations between, individuals; they are ‘predicates’ with variable extension. A current case of a system modelled by a Pr/T-net is denoted by marking the places with those tuples of individual symbols for which the respective predicates hold in that case. The transitions (boxes) are schemes of elementary changes of markings constituting the processes carried by the system. Instances of these schemes are generated by means of consistent substitution of individual variables by symbols.

Distribution Models Of Relations

Abstract: We show how relations can be modelled in fast memory by a distribution of tuples in a multidimensional space. Given distributions for operand relations we derive distributions for the relations that result from applying the relational algebra. We apply the result for the natural join to optimize the evaluation of an expression involving two joins. We suggest further applications. The analysis for division leads to a generalization of that operator.

Block coding for discrete stationary d -continuous noisy channels

Abstract: A new class of discrete stationary noisy channels with memory and anticipation termed d-continuous channels is introduced and is shown to include all stationary discrete channels for which coding theorems exist. Roughly speaking, in a \bar{d} -continuous channel the effect of the "past" and "future" inputs on n successive outputs dies out asymptotically with n as measured in a \bar{d} or average Hamming distance sense. This is weaker than the corresponding uotious of Pfaffeihuber, Kadota, and Wyner, who require that probabilities of all n -tuples be close; that is, closeness in a variational or distribution sense. General block channel coding and block joint source and channel coding theorems are proved for stationary \bar{d} -continuous channels, and various definitions of channel capacity are compared.

The complexity of testing predicate locks

Abstract: The problem of testing predicates for satisfiability arises in several aspects of database systems such as the use of predicate locks in concurrency control [7]. Such problems are NP-complete even for "simple predicates", i.e. predicates consisting of Boolean combinations of comparisons between a field of a tuple and a constant. However, when the relations referred to by the predicates are of fixed degree, there is an algorithm whose runtime is bounded by a polynomial in the length of the predicate. This is true not only for "simple predicates" but also for predicates containing comparisons between a field and another field, possibly offset by a constant. The proofs involve showing that if a predicate is satisfiable, then it is satisfiable by a tuple whose field values are related to constants occurring in the predicate.

Improving semantic specification in a relational database

Abstract: Standard semantics for the relational model considers domain values to be objects, which assume the roles indicated by the name of its associated attribute. Entities are related to each other to form tuples in a relation; attributes are also interrelated, but in this case the exact relationships have always been left implied or "intuitive." This paper introduces renaming rules, which are a way to formally specify these relationships. Properties of these rules are discussed, and a complete axiomatization is presented.Renaming rules allow meaningful equi-joins to be couched in terms of natural joins. They are intimately associated with the abstraction concept of generalization, and provide a natural semantics and theory for the relational algebraic operatiors select and union. These operators in turn use Smith's subcategory functional dependencies to achieve a better decomposition of a database scheme; to this end, a general normal form algorithm is presented.

On the Number of Comparisons to Find the Intersection of Two Relations

Abstract: Given two finite sets of k-tuples whose component elements are drawn from an infinite totally ordered set, the problem of identifying the k-tuples which belong to both sets is considered. Attention is restricted to algorithms that perform pairwise comparisons on the component elements of the k-tuples. If the two sets have cardinalities m and n with $m \leqq n$ it is shown that, in the worst case, \[ (m + n) \cdot \log _2 m + (m + n - 1)k \] comparisons are sufficient and \[ \max ((m + n) \cdot \log _2 m - 2.9m,(m + n - 1)k) \] comparisons are necessary. Upper and lower bounds are also given for the number of comparisons required to recognize duplicate tuples in a sequence of tuples, and to determine the lexicographic order of a sequence of tuples. In all cases, the disparity between the upper and lower bounds is at most a factor of two asymptotically.

AESOP: an architectural relational database

Abstract: This paper describes the principles and implementation of AESOP, an architectural relational database which aims to integrate building design procedures and to provide good graphic manipulation facilities. It is also intended to be highly flexible in that it allows inexact as well as exact data, can support a variety of user views of data and modes of use, and can accommodate itself to new techniques as these become available. AESOP uses ‘fuzzy’ logic. It holds information in the form of components which are linked lists of records, or relations, which are linked lists of tuples containing pointers to records, or, more generally, as directed graphs with records at the boundaries. New relations can be defined interactively from old using set theoretic operations thus enabling the logical operations of the first order predicate calculus to be performed on relations. The database also holds internal procedures called maps. Maps may be used to transform data as required by the user or to test the properties of a design proposal. New maps can be defined interactively from existing maps by applying composition, recursion or the logical operations of the first order calculus. An example of the use of the principles of fuzzy logic for guiding the selection of building fabriċ is given. Some tests of AESOP in practice on live problems are noted. It is concluded that AESOP could provide a useful framework for a CAAD system and that further work is required in two areas, the user interface, and operations involving geometrical relations.

The elements of SETL style.

Abstract: Associated with every programming language is a style of programming which is encouraged by the semantic and syntactic features of this language. We are all familiar with the phenomenon of a FORTRAN programmer approaching APL for the first time and writing correct APL programs which are nevertheless emphatically criticized for not displaying the proper APL style. Indeed we may consider this 'APL style' to be the most important contribution of the language to the art of programming, rather than the specific language features out of which this style emerges. Controversies about the value of APL (and other programming languages) focus precisely around this issue of style. It is also around this issue that we want to center our presentation of SETL.Briefly stated, SETL is a very-high level programming language whose basic semantic constructs are those of the mathematical theory of sets. Primitive operations in SETL include set membership, union, intersection, power set construction, etc. SETL provides two basic aggregate data types : unordered sets, and sequences, or tuples. The elements of sets and the components of tuples can themselves be of arbitrary type, including sets and tuples. In particular, sets of pairs (i.e. tuples of length 2) can be used as maps with perfectly general domain and range types.

Database Concurrent Processor

Abstract: The organization of an autonomous processor supporting database management functions is presented. The DataBase Concurrent Processor (DBCP) can be thought as a back-end data management machine of a general purpose host computer; it supports relational data model directly in hardware, and is able to run concurrently a number of programs written with a relationally complete instruction set. DBCP is composed of a parallel organization of cells and a Coordination Unit (CU). Each cell supports and processes tuples of an unique relation and consists of a special purpose microprocessor and a circulating serial memory. Along a full. memory revolution each microprocessor accomplishes an access on its own memory block while, at the same time, the CU transmits all necessary information to the access to be made in the next revolution. CU is allowed by microprocessor functional independence to organize different concurrency control strategies, trying to make maximum use of cellular organization processing capability. This concurrent processing capability at backend level fits better to the database system multiuser nature (shared resources) and consequently higher capabilities and performance rates are hoped to be achieved.

Use of abstracted characteristics of data in relational databases

Abstract: In the database field, the requirement of high level facilities for retrieval/update operations is now increasing rapidly. Our approach from the relational database point of view for contribution to this problem is to provide 1) efficient processing of relational retrieval/ update operations, and 2) a high level user interface. In order to achieve this goal, a new concept concerning "abstracted characteristics" is presented. Abstracted characteristics are defined to be characteristics abstracted from sets of tuples in relations stored in the database. A classification of abstracted characteristics is presented. Functional dependencies, which play an important role in relational database design, and time-dependent functional dependencies are pointed out to be useful in processing retrieval/update operations. Some important applications of abstracted characteristics are discussed. Among them: 1) efficient processing of retrieval/update operations, 2) powerful view update checking facilities, 3) providing some rough meanings of null responses and 4) a high level user interface.

A method of generating Pythagorean n‐tuples

Abstract: (1979). A method of generating Pythagorean n‐tuples. International Journal of Mathematical Education in Science and Technology: Vol. 10, No. 2, pp. 293-294.

On query-answering in relational data bases

Abstract: In recent years the relational model has been widely adopted for data base description. According to this model a data base, DB, describes certain objects of the world having certain attributes, and the relationships among them. Thus, DB is characterized by a set of attributes, D , a set of domains associated with the attributes, and a set of dependencies, F , corresponding to the relationships among the attributes (all the terms and concepts not defined here are those of References 1 – 3 ). A data base is a collection of relations, R ={ R i }. Each relation R i is characterized by a set of attributes S i ={ D j | D j ∈ D } called its scheme , and consists of a set of tuples. Each tuple is a map from the attributes of the relation scheme to their domains that satisfies all the dependencies of F (we shall consider functional dependencies).