Omar Ochoa

Using Pairwise Testing to Verify Automatically-Generated Formal Specifications

In this paper, we report on the effectiveness of the testing approach known as pairwise or orthogonal testing in verifying the correctness of the LTL specifications generated by the PROperty SPECification (Prospec) tool. This tool assists the user in generating a large number (over 34,000) of formal specifications in formal languages, including Linear Temporal Logic (LTL). Pairwise testing is a technique that aims at, significantly, reducing the amount of test cases required for testing a particular software system while providing assurance of adequate coverage of the problem space.

How to Gauge Accuracy of Measurements and of Expert Estimates: Beyond Normal Distributions

To properly process data, we need to know the accuracy of different data points, i.e., accuracy of different measurement results and expert estimates. Often, this accuracy is not given. For such situations, we describe how this accuracy can be estimated based on the available data.

JavaMaC and runtime monitoring for geoinformatics grid services

The Geoscience Network (GEON) project is a collaborative effort among numerous institutions to create the geoinformatics infrastructure. Because of the criticality of the grid services that is deployed, scientists need assurance of the integrity of the data supplied by the service and assurance that the workflows and other scientific applications behave as expected. This paper describes the efforts toward using the Kepler workflow system to define new applications, the prospec specification tool to define properties, and the JavaMac system to monitor grid services. In addition, it outlines the research questions and challenges that must be addressed to meet the requirements of the GEON community.

Fusing continuous and discrete data, on the example of merging seismic and gravity models in geophysics

In many application areas, we need to fuse continuous and discrete models of the same phenomena. For example, in geophysics, we have two main models for describing how the sound velocity changes with location and depth: a discrete gravity-based model, in which we have several layers with abrupt transition between layers, and a seismic model, in which the velocity continuously changes with the change in location and depth — and a transition is represented by a steeper change. Due to inevitable uncertainty, in two fused models, the same actual transition is placed at slightly different depths. If we simply fuse these models, the fused model will inherit both nearby transitions and therefore, will, misleadingly, correspond to two nearby transitions instead of one. It is therefore necessary, before fusing, to first get a fused (more accurate) location of the transition surface. In this paper, we show how to find such a location.

A comparative study of a tool-based approach for teaching formal specifications

The use of formal methods in software engineering has been shown to be an effective way to improving the dependability of developed systems. The difficulty of writing, reading, and understanding formal specifications, which is an essential component of formal verification, remains one of the main obstacles in the adoption of formal methods in industry. It is, thus, essential that undergraduate students in computing programs learn how to specify formal system properties. This paper outlines an instructive component that uses a tool to support the teaching of formal approaches and languages, and it presents educational outcomes from using such a component in undergraduate courses. The component uses a model checking-based tool LTLV to teach Linear Temporal Logic (LTL), a well-known specification language. In addition, this paper describes two experiments that compare the effectiveness of the new approach to that of the traditional lecture-based approach. The results of the experiments show promise that the tool-based approach can be effective in teaching formal specifications. The paper provides analysis of the results of the studies, as well as lessons learned from the experiments.

Towards a tool for generating aspects from MEDL and PEDL specifications for runtime verification

This paper describes an approach to generate AspectJ aspects from formal specifications written for the Monitoring and Checking (MaC) runtime verification tool. The aspects can serve as the foundation for instrumentation of programs that can be verified at runtime. To demonstrate the practicability of the proposed approach, the authors used a benchmark from the MaC research. The benchmark is based on a safety-critical railroad crossing system comprised of a train, a gate, and a controller. Finally, the paper describes the results from generating Java-MaCs specification scripts to AspectJ aspects, and it compares the proposed approach to related approaches and ones that use aspects.