A quantitative charcterization of control flow context: software measures for programming environments

A review of published measures of control flow complexity in programs reveals three major deficiencies: loss of information, lack of specificity, and lack of analytical support. A new approach is used to characterize the control structure of a program, with the aim of defining properties and measures of control flow that can be of immediate use to programmers, regardless of their utility as complexity measures. Mathematical rigor and analytical evaluation techniques are used to define a set of properties of control structure and a corresponding vector of measures. Instead of defining the properties and measures for an entire flowgraph, they are defined at the node level, reflecting the control flow surrounding each node in a flowgraph. The properties and their measures reflect the following characteristics of control flow: nesting, iteration, structuredness, and predecessors. Algorithms for computing the properties and their measures are presented. An assessment of the computational complexity of the algorithms shows that they are feasible programming environment tools;A finite path set, representing all possible execution sequences, is evaluated as a characterizing property. Desired characteristics of the path set are defined and used to evaluate four published path subset criteria. Those criteria are shown to be deficient, so a fifth criterion is defined. However, the path set satisfying this fifth criterion is shown to be too large to be of practical use to a programmer

Proceedings of the 1968 Summer Institute on Symbolic Mathematical Computation

Investigating symbolic mathematical computation using PL/1 FORMAC batch system and Scope FORMAC interactive syste

Programmiersprachen und Rechenkonzepte

Seit 1984 veranstaltet die GI-Fachgruppe "Programmiersprachen und Rechenkonzepte", die aus den ehemaligen Fachgruppen 2.1.3 "Implementierung von Programmiersprachen" und 2.1.4 "Alternative Konzepte für Sprachen und Rechner" hervorgegangen ist, regelmäßig im Frühjahr einen Workshop im Physikzentrum Bad Honnef. Das Treffen dient in erster Linie dem gegenseitigen Kennenlernen, dem Erfahrungsaustausch, der Diskussion und der Vertiefung gegenseitiger Kontakte

IST Austria Thesis

Motivated by the analysis of highly dynamic message-passing systems, i.e. unbounded thread creation, mobility, etc. we present a framework for the analysis of depth-bounded systems. Depth-bounded systems are one of the most expressive known fragment of the π-calculus for which interesting verification problems are still decidable. Even though they are infinite state systems depth-bounded systems are well-structured, thus can be analyzed algorithmically. We give an interpretation of depth-bounded systems as graph-rewriting systems. This gives more flexibility and ease of use to apply depth-bounded systems to other type of systems like shared memory concurrency. First, we develop an adequate domain of limits for depth-bounded systems, a prerequisite for the effective representation of downward-closed sets. Downward-closed sets are needed by forward saturation-based algorithms to represent potentially infinite sets of states. Then, we present an abstract interpretation framework to compute the covering set of well-structured transition systems. Because, in general, the covering set is not computable, our abstraction over-approximates the actual covering set. Our abstraction captures the essence of acceleration based-algorithms while giving up enough precision to ensure convergence. We have implemented the analysis in the PICASSO tool and show that it is accurate in practice. Finally, we build some further analyses like termination using the covering set as starting point

Systems tableau : an integrated approach to systems theory

Systems Tableau is suggested as a convenient tool for the integration of the three phases of systems theory: the synthesis of a model from the analysis of a system; the evaluation of the model; and the decision-making process for the design and control of the resulting system. From a basic consideration of Man-Nature communications, several mathematical, biological, engineering, and management examples of systems models are examined to develop a unified definition of a system. Logical, physical, mathematical, graphic, and computational requirements are postulated for the methodology of models for systems meeting the definition. These requirements are used to formulate the basic tableau as a hybrid of a mathematical mapping matrix and a graphical flowgraph that expresses the interrelationships among the components of a given system. Thus, a tableau is at once a matrix and a network representation of the system. The general (connecting), ordinal (dominating), and technological (directing) relations in the observation (phase) space are illustrated on tableaux for social, economic, management, and engineering examples. Related mathematics of relations are examined. The relationships of these descriptive models to normative models are discussed as synthesis techniques. Orthogonalization of bases, parametric representations (in frequency space as probabilities and statistical distributions), and reductions in state (solution) space are methods introduced with examples in queueing, communication, and information models. In normative models, we are afforded some degrees of freedom expressed in terms of choice of alternatives. This decision requires at least an ordinal, if not cardinal, characterization of each alternative. The ordinally normative models are based on comparatively quantifiable relations originally afforded by the uni-directional flow of time. Theories of Information, Algorithms, and Games were found useful in drawing valuable conclusions (decisions) from these models. Puzzles, games, Turing machines, and biological examples are discussed. The cardinally normative models require decisions based on numerical values. A truly cardinal model must be cardinal resource-wise, time-wise, and information-wise. This inter-dependency of resources in phase space and information in state space, as functions of time expressible in frequency space, is the basis for the proposal of the Cardinal Utility Hypotheses. This concept allows the development of relations as peculiar Laplace-Z transform-pairs, with the utility of Information (usefulness of data for decision-making) serving as the Channel Capacity for a corresponding communication model. The Principle of Optimality of Dynamic Programming was found most useful in Tableau, andits continuous counterpart of Maximum Principle is expected to take a respective place in the Calculus of Variations in Control Theory. The relationship of the controllability and observability of a system and the diagonalization of its Tableau is also illustrated. The linear models of the traditional Tableaux are reviewed and interpreted in the light of Systems Tableau Method, These include Quesney-Leontief Tableau Economique, Hellerman's Tableau, and Critical Path Scheduling Tableau. The obvious advantages afforded by the applications of Huggins' (and others) Signal Flowgraph techniques are briefly illustrated. Mention is made of a tableau-based computer program that will produce the dual network for Ford-Fulkerson's Minimum-cut-maximal-flow Method. A brief discussion of the future of Systems Theory concludes the treatise