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Xie D.,Software Techniques | Bu L.,Software Techniques | Zhao J.,Software Techniques | Li X.,Software Techniques
Formal Methods in System Design | Year: 2014

As discrete jumps and continuous flows tangle in the behavior of linear hybrid automata (LHA), the bounded model checking (BMC) for reachability of LHA is a challenging problem. Current works try to handle this problem by encoding all the discrete and continuous behaviors in the bound into a set of SMT formulas which can then be solved by SMT solvers. However, when the system size is large, the object SMT problem could be huge and difficult to solve. Instead of encoding everything into one constraint set, this paper proposes a SAT-LP-IIS joint-directed solution to conduct the BMC for reachability of LHA in a layered way. First, the bounded graph structure of LHA is encoded into a propositional formula set, and solved by SAT solvers to find potential paths which can reach the target location on the graph. Then, the feasibility of certain path is encoded into a set of linear constraints which can then be solved by linear programming (LP) efficiently. If the path is not feasible, irreducible infeasible set (IIS) technique is deployed to locate an infeasible path segment which will be fed to the SAT solver to accelerate the enumerating process. Experiments show that by this SAT-LP-IIS joint-directed solution, the memory usage of the BMC of LHA is well-controlled and the performance outperforms the state-of-the-art SMT-style competitors significantly. © 2014 Springer Science+Business Media New York.


Rong G.,Software Techniques | Zhang H.,Software Techniques | Shan Q.,Software Techniques | Liu G.,Software Techniques | Shao D.,Software Techniques
Proceedings - Asia-Pacific Software Engineering Conference, APSEC | Year: 2016

Background: Code inspection has been accepted as an effective method to detect and remove defects and code reading is a critical step in code inspection. However, there are very limited empirical studies on the content and appropriate forms of the suitable software artifacts as the supporting materials, hence inspectors may not be well-supported with necessary knowledge to carry out code reading. Objective: This research aims to investigate the impact of different common supporting materials (i.e., comments vs. design documents) on code reading. Method: A relatively large-scale controlled experiment with 135 senior students was designed and executed to compare the impacts of different supporting materials on code reading. The subjects were randomly separated into three groups with different treatments, i.e, the comments, the design documents and the comments+design documents, respectively. Two metrics regarding the code reading performance (i.e., Effectiveness and Defect Detection Rate) were used to compare the different impacts derived from the two different types of supporting materials. Qualitative feedbacks were also collected using questionnaires for the final analysis. Results: The results indicate that students performed better when being provided with comments than comments+design documents. Also, the removal of design documents shows little impact on inspection effectiveness and may lead to an increase in defect detection rate. Conclusion: Comments may provide more help and value than design documents as supporting material in small to median sized code reading. © 2015 IEEE.


Chen S.,Software Techniques | Li J.,Software Techniques | Wang X.,University of Sydney
Proceedings - 6th International Conference on Image and Graphics, ICIG 2011 | Year: 2011

Euclidean distance transform is widely used in many applications of image analysis and processing. Traditional algorithms are time-consuming and difficult to realize. This paper proposes a novel fast distance transform algorithm. Firstly, mark each foreground's nearest background pixel's position in the row and column; and then use the marks scan the foreground area and figure out the first foreground pixel distance transform information; According to the first pixel' information, design four small regions for its 4-adjacent foreground pixel and also based on the marks search out each adjacent foreground pixel's nearest background pixel. As the region growing, iteratively process each adjacent pixel until all the foreground pixels been resolved. Our algorithm has high efficiency and is simple to implement. Experiments show that comparing to the existing boundary striping and contour tracking algorithm, our algorithm demonstrates a significant improvement in time and space consumption. © 2011 IEEE.


Liu G.,Nanjing University | Rong G.,Software Techniques | Zhang H.,Nanjing University | Shan Q.,Nanjing University
ACM International Conference Proceeding Series | Year: 2015

Context: Capture-recapture method has long been adopted in software engineering as a relatively objective way for de- fect estimation. While many relevant studies have been carried out to evaluate various capture-recapture models and estimators, there still lacks common understanding on the adoption status of the method in software engineering. It is necessary to systematically collect empirical evidence of Capture-recapture adoption hence form necessary under- standing on the method. Objective: This study aims to synthesize relevant primary studies on the adoption of capture-recapture method in soft- ware engineering, and try to identify possible gaps between the state-of-practice and the state-of-art so as to provide clues for future research. Method: By following the guidelines of Kitchenham, we conducted a Systematic Literature Review(SLR) on studies of the adoption of capture-recapture method in software en- gineering. Results: From 5 common digital libraries, we retrieved 506 published articles, among them 44 were identified as relevant primary studies. We identified 18 capture-recapture estima- tors under 4 basic models. Types of the currently existing studies as well as the relevant in uencing factors to adoption of the capture-recapture method are also discussed. Conclusion: Results show that there are no conclusive de- cisions on the best capture-recapture models and estimators. Besides, the number of inspectors and their capability to de- tect defects as well as the difficulty to detect defects are most critical in uencing factors. In addition, lacking of industrial application may be the major issue of current adoption sta- tus of capture-recapture method in software engineering. Copyright 2015 ACM.


Chen S.,Software Techniques | Li J.,Software Techniques | Wang X.,University of Sydney
Journal of Computational Information Systems | Year: 2011

Euclidean distance transform is widely used in many applications of image analysis and pattern recognition. Traditional algorithms are time-consuming and complicated to realize. This paper proposes a fast marker-based distance transform algorithm. Firstly, mark the background pixels' positions relative to the object pixels; secondly, scan the object area and define the first object pixel as the parent pixel, and calculate its distance transform information; then, according to the parent pixel's information, the distance transform information of the object pixels (son pixels) which are 4-adjacent to the parent pixel is calculated successively; and finally, iteratively choose each son pixel as a parent pixel and manipulate its son pixels until all the object pixels have been resolved. Our algorithm has linear time complexity and is easy to implement. Experiments show that comparing to the existing boundary striping and contour tracking algorithm, our algorithm demonstrates a significant improvement in time and space complexity. © 2011 Binary Information Press December, 2011.


Xie D.,Software Techniques | Xiong W.,Software Techniques | Bu L.,Software Techniques | Li X.,Software Techniques
IEEE Transactions on Computers | Year: 2016

Reachability analysis of linear hybrid automata (LHA) is an important problem. Classical model checking (CMC) technique is not scalable and not guaranteed to terminate. On the other hand, bounded model checking (BMC) is more cost-effective to conduct but can not guarantee the safety beyond the bound. In this paper, we seek to bridge the gap between BMC and CMC for reachability analysis of LHA. During BMC of LHA, typical procedures can discover sets of unsatisfiable constraint cores, which can be mapped back to path segments in the graph structure of LHA. If every path connecting the initial and target location has to go through such infeasible path segment, the target location is entirely not reachable. Based on this characteristic, we propose a LTL model checking based approach to check whether the target location is blocked. To further optimize the performance, we propose an automata based solution to check the LTL specification incrementally and adopt an on-the-fly algorithm to check the accepting condition to avoid an explicit construction of product automata. © 2016 IEEE.


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