8542310
Abstract Model Checking of Infinite Specifications
A new method for analyzing specifications in languages like Z and VDM is proposed. Theorems are checked automatically by exhaustive search of the state space. An abstraction over the actual states can be defined that reduces an infinite state space to a finite number of equivalence classes, allowing it to be searched exhaustively by treating each class as a single abstract state. A prototype has been built that has verified some small theorems from the literature.
946209
A new model of program dependences for reverse engineering
A dependence model for reverse engineering should treat procedures in a modular fashion and should be fine-grained, distinguishing dependences that are due to different variables. The program dependence graph (PDG) satisfies neither of these criteria. We present a new form of dependence graph that satisfies both, while retaining the advantages of the PDG: it is easy to construct and allows program slicing to be implemented as a simple graph traversal. We define 'chopping', a generalization of slicing that can express most of its variants, and show that, using our dependence graph, it produces more accurate results than algorithms based directly on the PDG.
15229178
Faster checking of software specifications by eliminating isomorphs
Both software specifications and their intended properties can be expressed in a simple relational language. The claim that a specification satisfies a property becomes a relational formula that can be checked automatically by enumerating the formula's interpretations. Because the number of interpretations is usually huge, this approach has not been thought to be practical. But by eliminating isomorphic interpretations, the enumeration can be reduced substantially, with a factor of roughly k! contributed by each type of k elements.
13527146
An Agent-Based Behavioural Model of Monomorium Pharaonis Colonies
In this study X-machines and hierarchical organized X-machines will be used to model different aspects of the behaviour of social insect communities. The model is organized as a community of complex agents showing similarities to networks of P systems.
13957173
Lightweight extraction of object models from bytecode
A program's object model captures the essence of its design. For some programs, no object model was developed during design; for others, an object model exists but may be out of sync with the code. The paper describes a tool that automatically extracts an object model from the class files of a Java program. Although the tool performs only a simple, heuristic analysis that is almost entirely local, the resulting object model is surprisingly accurate. The paper explains the form of the object model, the assumptions upon which the analysis is based, and its limitations, and evaluates the tool on a suite of sample programs.
35077963
A Combinatorial Relationship between Eulerian Maps and Hypermaps in Orientable Surfaces
Abstract There is a remarkable relationship between the genus series for rooted maps and rooted quadrangulations that has been obtained by a character theoretic argument. Hitherto no combinatorial explanation for this has been given. In this paper we generalize this relationship to a larger set of maps for which such a relationship can be found and we ascertain some of the properties that a putative bijection must possess. Several examples of images of sets under this bijection are given. We give them in detail since they may contain useful information about the bijection.
14356359
Decision and Separability Problems for Baumslag-Solitar Semigroups
We show that the semigroups Sk,l having semigroup presentations are residually finite and finitely separable. Generally, these semigroups have finite separating images which are finite groups and other finite separating images which are semigroups of order-increasing transformations on a finite partially ordered set. These semigroups thus have vastly different residual and separability properties than the Baumslag–Solitar groups which contain them.
40941890
The Quadrangulation Conjecture for Orientable Surfaces
By means of character theory and symmetric functions, D. M. Jackson and T. I. Visentin (1990, Trans. Amer. Math. Soc. 322, (343-363)) proved the existence of certain bijections between the set of quadrangulations in orientable surfaces and decorated maps (with marked edges and coloured vertices) in orientable surfaces. The bijections preserve a weight function consisting of a pair (g,n) of integer parameters. For quadrangulations, g is the genus and n is the number of faces. For decorated maps, g is the genus plus half the number of white vertices and n is the number of edges. The Quadrangulation Conjecture concerns the problem of finding a natural bijection of this type. Tutte's medial construction is a solution in the special case g = 0 of planar maps. We give a construction of a bijection ??Ξ which both extends Tutte's medial construction to non-planar maps and preserves the parameter n of the Quadrangulation Conjecture. (The parameter g is not generally preserved, except when g = 0.) Non-orientable surfaces play an important part in the construction of ??Ξ. As part of the construction, we introduce a bijection between orientable rooted quadrangulations and locally orientable, bipartite, rooted quadrangulations.