Model Checker Execution Reports

Software model checking constitutes an undecidable problem and, as such, even an ideal tool will in some cases fail to give a conclusive answer. In practice, software model checkers fail often and usually do not provide any information on what was effectively checked. The purpose of this work is to provide a conceptual framing to extend software model checkers in a way that allows users to access information about incomplete checks. We characterize the information that model checkers themselves can provide, in terms of analyzed traces, i.e. sequences of statements, and safe cones, and present the notion of execution reports, which we also formalize. We instantiate these concepts for a family of techniques based on Abstract Reachability Trees and implement the approach using the software model checker CPAchecker. We evaluate our approach empirically and provide examples to illustrate the execution reports produced and the information that can be extracted

Dynamic Slicing by On-demand Re-execution

In this paper, we propose a novel approach that aims to offer an alternative to the prevalent paradigm to dynamic slicing construction. Dynamic slicing requires dynamic data and control dependencies that arise in an execution. During a single execution, memory reference information is recorded and then traversed to extract dependencies. Execute-once approaches and tools are challenged even by executions of moderate size of simple and short programs. We propose to shift practical time complexity from execution size to slice size. In particular, our approach executes the program multiple times while tracking targeted information at each execution. We present a concrete algorithm that follows an on-demand re-execution paradigm that uses a novel concept of frontier dependency to incrementally build a dynamic slice. To focus dependency tracking, the algorithm relies on static analysis. We show results of an evaluation on the SV-COMP benchmark and Antrl4 unit tests that provide evidence that on-demand re-execution can provide performance gains particularly when slice size is small and execution size is large

Partial Behavioural Models for Requirements and Early Design

The talk will discuss the problem of creation, management, and specifically merging of partial behavioural models, expressed as model transition systems. We argue why this formalism is essential in the early stages of the software cycle and then discuss why and how to merge information coming from different sources using this formalism. The talk is based on papers presented in FSE\u2704 and FME\u2706 and will also include emerging results on synthesizing partial behavioural models from temporal properties and scenarios

An Inductive Approach for Modal Transition System Refinement

Modal Transition Systems (MTSs) provide an appropriate framework for modelling software behaviour when only a partial specification is available. A key characteristic of an MTS is that it explicitly models events that a system is required to provide and is proscribed from exhibiting, and those for which no specification is available, called maybe events. Incremental elaboration of maybe events into either required or proscribed events can be seen as a process of MTS refinement, resulting from extending a given partial specification with more information about the system behaviour. This paper focuses on providing automated support for computing strong refinements of an MTS with respect to event traces that describe required and proscribed behaviours using a non-monotonic inductive logic programming technique. A real case study is used to illustrate the practical application of the approach

Focused Dynamic Slicing for Large Applications using an Abstract Memory-Model

Dynamic slicing techniques compute program dependencies to find all statements that affect the value of a variable at a program point for a specific execution. Despite their many potential uses, applicability is limited by the fact that they typically cannot scale beyond small-sized applications. We believe that at the heart of this limitation is the use of memory references to identify data-dependencies. Particularly, working with memory references hinders distinct treatment of the code-to-be-sliced (e.g., classes the user has an interest in) from the rest of the code (including libraries and frameworks). The ability to perform a coarser-grained analysis for the code that is not under focus may provide performance gains and could become one avenue toward scalability. In this paper, we propose a novel approach that completely replaces memory reference registering and processing with a memory analysis model that works with program symbols (i.e., terms). In fact, this approach enables the alternative of not instrumenting -- thus, not generating any trace -- for code that is not part of the code-to-be-sliced. We report on an implementation of an abstract dynamic slicer for C\#, \textit{DynAbs}, and an evaluation that shows how large and relevant parts of Roslyn and Powershell -- two of the largest and modern C\# applications that can be found in GitHub -- can be sliced for their test cases assertions in at most a few minutes. We also show how reducing the code-to-be-sliced focus can bring important speedups with marginal relative precision loss

Fluent temporal logic for discrete-time event-based models

Fluent model checking is an automated technique for verifying that an event-based operational model satisfies some state-based declarative properties. The link between the event-based and state-based formalisms is defined through fluents which are state predicates whose value are determined by the occurrences of initiating and terminating events that make the fluents values become true or false, respectively. The existing fluent temporal logic is convenient for reasoning about untimed event-based models but difficult to use for timed models. The paper extends fluent temporal logic with temporal operators for modelling timed properties of discrete-time event-based models. It presents two approaches that differ on whether the properties model the system state after the occurrence of each event or at a fixed time rate. Model checking of timed properties is made possible by translating them into the existing untimed framework. Copyright 2005 ACM

Nube híbrida nacional: soberana, libre, interoperable y con desarrollo local

Recientemente la Secretaría de Innovación Pública ha convocado a un procedimiento de consulta para la concreción de una Nube Híbrida de Gobierno. El objetivo de la Consulta es recibir aportes, ideas, experiencias y recomendaciones para la definición de criterios tecnológicos que permitan la construcción de la misma. En este marco, quienes firmamos la presente, actores de diversas organizaciones del quehacer tecnológico nacional, mujeres y hombres con décadas de experiencia profesional en tecnologías informáticas y su relación con el desarrollo nacional, apoyamos la construcción de una Nube híbrida de Gobierno, saludamos el llamado a Consulta y acordamos en una serie de principios que creemos fundamentales para su desarrollo y el aseguramiento de la soberanía tecnológica.Fil: Monk, Leandro Nicolás. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Computación; ArgentinaFil: Schapachnik, Fernando. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigación en Ciencias de la Computación. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigación en Ciencias de la Computación; ArgentinaFil: Uchitel, Sebastian. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigación en Ciencias de la Computación. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigación en Ciencias de la Computación; ArgentinaFil: Vannini, Pablo Alberto. No especifíca;Fil: Zukerfeld, Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Investigación en Ciencias de la Computación. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Investigación en Ciencias de la Computación; ArgentinaFil: Díaz, Andrea. No especifíca;Fil: Dunayevich, Julián. No especifíca;Fil: Lagostena, Juan Pablo. No especifíca;Fil: Passerini, Pablo Nicolás. No especifíca