Height-relaxed AVL rebalancing: a unified, fine-grained approach to concurrent dictionaries

We show that this problem can be studied through the self-reorganization of distributed systems of nodes controlled by local evolution rules in the line of the approach of Dijkstra and Scholten. This yields a much simpler algorithm that the ones previously known. Based on the basic rebalancing framework, we describe algorithms to manage concurrent insertion and deletion of keys. Finally, this approach is used to emulate other well known concurrent AVL algorithms. As a by-product, this solves in a very general setting an old question raised by H.T. Kung and P.L. Lehman: where should rotations take place to rebalance arbitrary search trees

Ren Par '6 Lyon, 7-10 juin 1994

SIGLEAvailable at INIST (FR), Document Supply Service, under shelf-number : Y 30419 / INIST-CNRS - Institut de l'Information Scientifique et TechniqueFRFranc

An Axiom-Based Test Case Selection Strategy for Object-Oriented Programs

Because of the growing importance of object-oriented programming, a number of testing approaches have been proposed. Frankl et al. propose the application of the functional approach, using algebraic specifications for the generation of test cases and the validation of methods. Given a specification, Frankl et al. propose that equivalent terms should give observably equivalent objects, and offer general heuristics on the selection of equivalent terms for testing. Their guidelines, however, are only supported by limited empirical results, do not have a theoretical basis, and provide no guarantee of effectiveness. In this paper, we define the concept of a fundamental pair as a pair of equivalent terms which are formed by replacing all the variables on both sides of an axiom by normal forms. We prove that an implementation is consistent with respect to all equivalent terms if and only if it is consistent with respect to all fundamental pairs. In other words, the testing coverage of fundamental pairs is identical to that of all equivalent terms, and hence we need only concentrate on the testing of fundamental pairs. Our strategy is mathematically based, simple, and much more efficient. Furthermore, it underscores the usefulness of axiom-based specifications

Controllable combinatorial coverage in grammar-based testing

Abstract. Given a grammar (or other sorts of meta-data), one can trivially derive combinatorially exhaustive test-data sets up to a specified depth. Without further efforts, such test-data sets would be huge at the least and explosive most of the time. Fortunately, scenarios of grammar-based testing tend to admit nonexplosive approximations of naive combinatorial coverage. In this paper, we describe the notion of controllable combinatorial coverage and a corresponding algorithm for test-data generation. The approach is based on a suite of control mechanisms to be used for the characterization of test-data sets as well-defined and understandable approximations of full combinatorial coverage. The approach has been implemented in the C#-based test-data generator Geno, which has been successfully used in projects that required differential testing, stress testing and conformance testing of grammar-driven functionality.