Tortoise: Interactive System Configuration Repair

System configuration languages provide powerful abstractions that simplify managing large-scale, networked systems. Thousands of organizations now use configuration languages, such as Puppet. However, specifications written in configuration languages can have bugs and the shell remains the simplest way to debug a misconfigured system. Unfortunately, it is unsafe to use the shell to fix problems when a system configuration language is in use: a fix applied from the shell may cause the system to drift from the state specified by the configuration language. Thus, despite their advantages, configuration languages force system administrators to give up the simplicity and familiarity of the shell. This paper presents a synthesis-based technique that allows administrators to use configuration languages and the shell in harmony. Administrators can fix errors using the shell and the technique automatically repairs the higher-level specification written in the configuration language. The approach (1) produces repairs that are consistent with the fix made using the shell; (2) produces repairs that are maintainable by minimizing edits made to the original specification; (3) ranks and presents multiple repairs when relevant; and (4) supports all shells the administrator may wish to use. We implement our technique for Puppet, a widely used system configuration language, and evaluate it on a suite of benchmarks under 42 repair scenarios. The top-ranked repair is selected by humans 76% of the time and the human-equivalent repair is ranked 1.31 on average.Comment: Published version in proceedings of IEEE/ACM International Conference on Automated Software Engineering (ASE) 201

Certifying and removing disparate impact

What does it mean for an algorithm to be biased? In U.S. law, unintentional bias is encoded via disparate impact, which occurs when a selection process has widely different outcomes for different groups, even as it appears to be neutral. This legal determination hinges on a definition of a protected class (ethnicity, gender, religious practice) and an explicit description of the process. When the process is implemented using computers, determining disparate impact (and hence bias) is harder. It might not be possible to disclose the process. In addition, even if the process is open, it might be hard to elucidate in a legal setting how the algorithm makes its decisions. Instead of requiring access to the algorithm, we propose making inferences based on the data the algorithm uses. We make four contributions to this problem. First, we link the legal notion of disparate impact to a measure of classification accuracy that while known, has received relatively little attention. Second, we propose a test for disparate impact based on analyzing the information leakage of the protected class from the other data attributes. Third, we describe methods by which data might be made unbiased. Finally, we present empirical evidence supporting the effectiveness of our test for disparate impact and our approach for both masking bias and preserving relevant information in the data. Interestingly, our approach resembles some actual selection practices that have recently received legal scrutiny.Comment: Extended version of paper accepted at 2015 ACM SIGKDD Conference on Knowledge Discovery and Data Minin

MintHint: Automated Synthesis of Repair Hints

Being able to automatically repair programs is an extremely challenging task. In this paper, we present MintHint, a novel technique for program repair that is a departure from most of today's approaches. Instead of trying to fully automate program repair, which is often an unachievable goal, MintHint performs statistical correlation analysis to identify expressions that are likely to occur in the repaired code and generates, using pattern-matching based synthesis, repair hints from these expressions. Intuitively, these hints suggest how to rectify a faulty statement and help developers find a complete, actual repair. MintHint can address a variety of common faults, including incorrect, spurious, and missing expressions. We present a user study that shows that developers' productivity can improve manyfold with the use of repair hints generated by MintHint -- compared to having only traditional fault localization information. We also apply MintHint to several faults of a widely used Unix utility program to further assess the effectiveness of the approach. Our results show that MintHint performs well even in situations where (1) the repair space searched does not contain the exact repair, and (2) the operational specification obtained from the test cases for repair is incomplete or even imprecise

Public Perceptions of the Midwest’s Pavements - Wisconsin - Phase I (Focus Group)

This research is being conducted as part of a larger study of the public\u27s perceptions of state-maintained rural highway pavements in Wisconsin, Minnesota, and Iowa. Later stages of this project will involve interview;ing residents of the three states by telephone to gather information about people\u27s concerns about the pavements in general and specific stretches of highways in particular. Information from this effort is expected to aid the states\u27 Departments of Transportation refine the standards used to set pavement reconstruction priorities to better meet the needs of residents

Public Perceptions of the Midwest’s Pavements - Minnesota - Phase III (Targeted Survey Report)

This research is being conducted as part of a larger study of the public’s perceptions of state-maintained rural highway pavements in Wisconsin, Minnesota, and Iowa. Later stages of this project will involve interviewing residents of the three states by telephone to gather information about people’s concerns about the pavements in general and specific stretches of highways in particular. Information from this effort is expected to aid the states’ Departments of Transportation refine the standards used to set pavement reconstruction priorities to better meet the needs of residents

An Algorithmic Measurement of Technical Progress

In this paper we propose a measure of technological progress which is based on the information embedded in standard input-output tables. Well known duality properties enables one to establish a connection between the quantities necessary as inputs and the associated output and some auxiliary prices (like the wage-profit curves). We claim that properly tailored wage-profit frontiers may provide a basis for the measurement of technological progress. But the computation of these wage-profit frontiers is not trivial. A brute force algorithm for the computation of the wage-profit frontiers has high combinatorial complexity that would make its precise computation intractable. But thanks to an efficient algorithm that we have been able to devise we can now compute it. We consider this to be an important and original contribution. Here we present and apply this algorithm. Due to this improvement we can now use these wage-profit frontiers as benchmarks against which to measure technological progress: two new indices have been defined. These new tools have have been applied to the OECD input-output data 1970-2005 and the reslts are presented here.Technological Change, Convergence, Input-output analysis, Technological Frontier, Computational Techniques

Wage diversity in the euro area - an overview of labour cost differentials across industries

This Paper provides an overview of the magnitude of sectoral wage differentials in the euro area as a whole. Even when adjusting for structural sectoral features such as the skill structure or the proportion of part-timers, average wage levels in services are substantially lower than in manufacturing. The paper also studies how the euro area wage structure compares with that of the United States and the United Kingdom. It discusses some possible determinants of intersectoral wage differentials in the euro area and their likely implications from a policy perspective. A number of worker characteristics (e.g. age, skills, the proportion of temporary or self-employed) are highly correlated with the structure of wage differentials. At the same time, wage differentials are also highly correlated with sector-specific features such as average firm size or capital intensity. Finally, the paper presents some stylised facts on how the euro area wage structure has evolved since the early 1980s.Intersectoral wage differential; wage determination; euro area.

Public Perceptions of the Midwest’s Pavements - Minnesota - Phase I (focus group)

This research is being conducted as part of a larger study of the public’s perceptions of state-maintained rural highway pavements in Wisconsin, Minnesota, and Iowa. Later stages of this project will involve interviewing residents of the three states by telephone to gather information about people’s concerns about the pavements in general and specific stretches of highways in particular. Information from this effort is expected to aid the states’ Departments of Transportation refine the standards used to set pavement reconstruction priorities to better meet the needs of residents

Priority-Based Conflict Resolution in Inconsistent Relational Databases

We study here the impact of priorities on conflict resolution in inconsistent relational databases. We extend the framework of repairs and consistent query answers. We propose a set of postulates that an extended framework should satisfy and consider two instantiations of the framework: (locally preferred) l-repairs and (globally preferred) g-repairs. We study the relationships between them and the impact each notion of repair has on the computational complexity of repair checking and consistent query answers