An Instantiation-Based Approach for Solving Quantified Linear Arithmetic

This paper presents a framework to derive instantiation-based decision procedures for satisfiability of quantified formulas in first-order theories, including its correctness, implementation, and evaluation. Using this framework we derive decision procedures for linear real arithmetic (LRA) and linear integer arithmetic (LIA) formulas with one quantifier alternation. Our procedure can be integrated into the solving architecture used by typical SMT solvers. Experimental results on standardized benchmarks from model checking, static analysis, and synthesis show that our implementation of the procedure in the SMT solver CVC4 outperforms existing tools for quantified linear arithmetic

SAT-Based Synthesis Methods for Safety Specs

Automatic synthesis of hardware components from declarative specifications is an ambitious endeavor in computer aided design. Existing synthesis algorithms are often implemented with Binary Decision Diagrams (BDDs), inheriting their scalability limitations. Instead of BDDs, we propose several new methods to synthesize finite-state systems from safety specifications using decision procedures for the satisfiability of quantified and unquantified Boolean formulas (SAT-, QBF- and EPR-solvers). The presented approaches are based on computational learning, templates, or reduction to first-order logic. We also present an efficient parallelization, and optimizations to utilize reachability information and incremental solving. Finally, we compare all methods in an extensive case study. Our new methods outperform BDDs and other existing work on some classes of benchmarks, and our parallelization achieves a super-linear speedup. This is an extended version of [5], featuring an additional appendix.Comment: Extended version of a paper at VMCAI'1

Management of Road Infrastructure Safety

Road Infrastructure Safety Management (RISM) refers to a set of procedures that support a road authority in decision making related to the improvement of safety on a road network. Some of these procedures can be applied to existing infrastructure, thus enabling a reactive approach; and other procedures are used in early stages of a project's life-cycle allowing a proactive approach. The objective of this paper is to provide an overview of the most well-known procedures and present a series of recommendations for successful road infrastructure safety management. The work described in the paper was completed by the IRTAD sub-working group on Road Infrastructure Safety Management and presented in detail in the respective Report. The methodology followed on this purpose included the description of the most consolidated RISM procedures, the analysis of the use of RISM procedures worldwide and the identification of possible weaknesses and barriers to their implementation, the provision of good practice examples and the contribution to the scientific assessment of procedures. Specifically, the following RISM procedures were considered: Road Safety Impact Assessment (RIA), Efficiency Assessment Tools (EAT), Road Safety Audit (RSA), Network Operation (NO), Road Infrastructure Safety Performance Indicators (SPI), Network Safety Ranking (NSR), Road Assessment Programs (RAP), Road Safety Inspection (RSI), High Risk Sites (HRS) and In-depth Investigation. Each procedure was described along with tools and data needed for its implementation as well as relevant common practices worldwide. A synthesis summarizing the key information for each procedure was also drafted. Based on a survey on 23 IRTAD member countries from worldwide, the lack of resources or tools is the most commonly stated reason for not applying a RISM procedure. This has been frequently found mainly in European countries. Another common reason is the absence of recommendations/guidelines, especially for SPI, RAP, RSI and RSA. This highlights the importance of the presence of some legislation regulating the application of the procedures. Lack of data was found important mainly for SPI, HRS and EAT. Good practices of road infrastructure safety management have been explored in order to find solutions to the issues highlighted by the survey and provide examples about how these issues have been overcome in some countries. Specifically, issues related to data, legal framework, funding, knowledge, tools and dealing with more RISM procedures were addressed. Finally, nine key messages and six recommendations for better Road Infrastructure Safety Management were developed based on the conclusions made

Functional synthesis for linear arithmetic and sets

Synthesis of program fragments from specifications can make programs easier to write and easier to reason about. To integrate synthesis into programming languages, synthesis algorithms should behave in a predictable way—they should succeed for a well-defined class of specifications. To guarantee correctness and applicability to software (and not just hardware), these algorithms should also support unbounded data types, such as numbers and data structures. To obtain appropriate synthesis algorithms, we propose to generalize decision procedures into predictable and complete synthesis procedures. Such procedures are guaranteed to find the code that satisfies the specification if such code exists. Moreover, we identify conditions under which synthesis will statically decide whether the solution is guaranteed to exist and whether it is unique. We demonstrate our approach by starting from a quantifier elimination decision procedure for Boolean algebra of set with Presburger arithmetic and transforming it into a synthesis procedure. Our procedure also works in the presence of parametric coefficients. We establish results on the size and the efficiency of the synthesized code. We show that such procedures are useful as a language extension with implicit value definitions, and we show how to extend a compiler to support such definitions. Our constructs provide the benefits of synthesis to programmers, without requiring them to learn new concepts, give up a deterministic execution model, or provide code skeleton

Synthesis of Deterministic Top-down Tree Transducers from Automatic Tree Relations

We consider the synthesis of deterministic tree transducers from automaton definable specifications, given as binary relations, over finite trees. We consider the case of specifications that are deterministic top-down tree automatic, meaning the specification is recognizable by a deterministic top-down tree automaton that reads the two given trees synchronously in parallel. In this setting we study tree transducers that are allowed to have either bounded delay or arbitrary delay. Delay is caused whenever the transducer reads a symbol from the input tree but does not produce output. We provide decision procedures for both bounded and arbitrary delay that yield deterministic top-down tree transducers which realize the specification for valid input trees. Similar to the case of relations over words, we use two-player games to obtain our results.Comment: In Proceedings GandALF 2014, arXiv:1408.556

Environmental Application of Cyclodextrin Metal-Organic Frameworks in an Undergraduate Teaching Laboratory

Reported herein is a multidisciplinary laboratory experiment for advanced undergraduate students that includes elements of material synthesis, in the synthesis of cyclodextrin-containing metal–organic frameworks (CD-MOFs), and environmental chemistry, in the use of these MOFs for pollutant removal. This multiday laboratory experiment starts with the synthesis of cyclodextrin-containing metal–organic frameworks (CD-MOFs) using vapor diffusion crystal growth procedures, followed by the use of the CD-MOFs for a pollutant removal application. Specifically, the CD-MOFs were used for the removal of a methylene blue dye (a common mimic of aromatic pollutants) from an organic solution, with the monitoring of the success of the removal procedures using UV–vis spectroscopy. This experiment was implemented as part of a larger multiday unit, and undergraduate students were particularly engaged with and excited by the CD-MOF synthesis and methylene blue removal experimental modules. As a result, the decision was made to make these two components a stand-alone multidisciplinary laboratory experiment, the results of which are reported herein

Software Synthesis is Hard -- and Simple

While the components of distributed hardware systems can reasonably be assumed to be synchronised, this is not the case for the components of distributed software systems. This has a strong impact on the class of synthesis problems for which decision procedures exist: While there is a rich family of distributed systems, including pipelines, chains, and rings, for which the realisability and synthesis problem is decidable if the system components are composed synchronously, it is well known that the asynchronous synthesis problem is only decidable for monolithic systems. From a theoretical point of view, this renders distributed software synthesis undecidable, and one is tempted to conclude that synthesis of asynchronous systems, and hence of software, is much harder than the synthesis of synchronous systems. Taking a more practical approach, however, reveals that bounded synthesis, one of the most promising synthesis techniques, can easily be extended to asynchronous systems. This merits the hope that the promising results from bounded synthesis will carry over to asynchronous systems as well

Procedural justice and public involvement in natural resource decision making

This thesis examines the application of findings from the social psychological field of procedural justice to public involvement in natural resource decision making. The methodological approach involves examining the literature of each of the fields and developing a synthesis applicable to public involvement. The review of public involvement literature reveals a variety of reasons for involving the public in decision making, but little attention to the effects of procedures on participants. However, a comparison and synthesis of the principle findings of the two disciplines indicates important procedural elements for public participation programs, including (1) procedural justice supports process related goals for public involvement; (2) public participation procedures should be inclusive; (3) public participation procedures should provide for interactive approaches; (4) procedural preferences are situationally specific; (5) decision makers must provide clear justification for their decisions; and (6) decision makers must maintain the appearance of impartiality. These findings lead to a rejection of the positivist ideology that has dominated public involvement literature and the development of a new theory of public involvement that recognizes the importance of both outcomes and procedures. Finally, the thesis discusses issues regarding the application of this theory to public involvement programs, including issues relating to interest groups, non-participants, historical mistrust, the meanings of satisfaction and dissatisfaction, and measures of fairness