Fast generation of lexicographic satisfiable assignments: enabling canonicity in SAT-based applications

Lexicographic Boolean satisfiability (LEXSAT) is a variation of the Boolean satisfiability problem (SAT). Given a variable order, LEXSAT finds a satisfying assignment whose integer value under the given variable order is minimum (maximum) among all satisfiable assignments. If the formula has no satisfying assignments, LEXSAT proves it unsatisfiable, as does the traditional SAT. The paper proposes an efficient algorithm for LEXSAT by combining incremental SAT solving with binary search. It also proposes methods that use the lexicographic properties of the assignments to further improve the runtime when generating consecutive satisfying assignments in lexicographic order. The proposed algorithm outperforms the state-of-the-art LEXSAT algorithm—on average, it is 2.4 times faster when generating a single LEXSAT assignment, and it is 6.3 times faster when generating multiple consecutive assignments

Synthesis and Optimization of Reversible Circuits - A Survey

Reversible logic circuits have been historically motivated by theoretical research in low-power electronics as well as practical improvement of bit-manipulation transforms in cryptography and computer graphics. Recently, reversible circuits have attracted interest as components of quantum algorithms, as well as in photonic and nano-computing technologies where some switching devices offer no signal gain. Research in generating reversible logic distinguishes between circuit synthesis, post-synthesis optimization, and technology mapping. In this survey, we review algorithmic paradigms --- search-based, cycle-based, transformation-based, and BDD-based --- as well as specific algorithms for reversible synthesis, both exact and heuristic. We conclude the survey by outlining key open challenges in synthesis of reversible and quantum logic, as well as most common misconceptions.Comment: 34 pages, 15 figures, 2 table

Heuristic NPN classification for large functions using AIGs and LEXSAT

Two Boolean functions are NPN equivalent if one can be ob- tained from the other by negating inputs, permuting inputs, or negating the output. NPN equivalence is an equivalence relation and the number of equivalence classes is significantly smaller than the number of all Boolean functions. This property has been exploited successfully to in- crease the efficiency of various logic synthesis algorithms. Since computing the NPN representative of a Boolean function is not scalable, heuristics have been proposed that are not guaranteed to find the representative for all functions. So far, these heuristics have been implemented using the function’s truth table representation, and therefore do not scale for functions exceeding 16 variables. In this paper, we present a symbolic heuristic NPN classification using And-Inverter Graphs and Boolean satisfiability techniques. This allows us to heuristically compute NPN representatives for functions with much larger number of variables; our experiments contain benchmarks with up to 194 variables. A key technique of the symbolic implementation is SAT-based procedure LEXSAT, which finds the lexicographically smallest satisfiable assignment. To our knowledge, LEXSAT has never been used before in logic synthesis algorithms

Assessing the quality of reports of systematic reviews in pediatric complementary and alternative medicine

OBJECTIVE: To examine the quality of reports of complementary and alternative medicine (CAM) systematic reviews in the pediatric population. We also examined whether there were differences in the quality of reports of a subset of CAM reviews compared to reviews using conventional interventions. METHODS: We assessed the quality of reports of 47 CAM systematic reviews and 19 reviews evaluating a conventional intervention. The quality of each report was assessed using a validated 10-point scale. RESULTS: Authors were particularly good at reporting: eligibility criteria for including primary studies, combining the primary studies for quantitative analysis appropriately, and basing their conclusions on the data included in the review. Reviewers were weak in reporting: how they avoided bias in the selection of primary studies, and how they evaluated the validity of the primary studies. Overall the reports achieved 43% (median = 3) of their maximum possible total score. The overall quality of reporting was similar for CAM reviews and conventional therapy ones. CONCLUSIONS: Evidence based health care continues to make important contributions to the well being of children. To ensure the pediatric community can maximize the potential use of these interventions, it is important to ensure that systematic reviews are conducted and reported at the highest possible quality. Such reviews will be of benefit to a broad spectrum of interested stakeholders

Lightweight String Reasoning for OCL

International audienceModels play a key role in assuring software quality in the modeldriven approach. Precise models usually require the definition of OCL expressions to specify model constraints that cannot be expressed graphically. Techniques that check the satisfiability of such models and find corresponding instances of them are important in various activities, such as model-based testing and validation. Several tools to check model satisfiability have been developed but to our knowledge, none of them yet supports the analysis of OCL expressions including operations on Strings in general terms. As, in contrast, many industrial models do contain such operations, there is evidently a gap. There has been much research on formal reasoning on strings in general, but so far the results could not be included into model finding approaches. For model finding, string reasoning only contributes a sub-problem, therefore, a string reasoning approach for model finding should not add up front too much computational complexity to the global model finding problem. We present such a lightweight approach based on constraint satisfaction problems and constraint rewriting. Our approach efficiently solves several common kinds of string constraints and it is integrated into the EMFtoCSP model finder

The motivations of external whistleblowers and their impact on the intention to blow the whistle again

The purpose of this study was to inquire into the relative importance of morality, cost‐benefit, and emotion as motivations for the decision to blow the whistle externally, and the effects of such factors as motivations, perceived negative consequences, and preferences for reform on the intention to blow the whistle again. Based on a literature review, we formulated some hypotheses and, to test them, we used the data collected from a survey of 127 external whistleblowers in South Korea. The results revealed that morality was the most important motivation, followed by emotion, and then cost‐benefit, which thus, seemed to be the least important for the whistleblowers. Morality as a motivation and the perceived negative consequences of whistleblowing had a significant effect on the intention to blow the whistle again. This study helps advance the understanding of the motivations behind whistleblowing and the factors that influence the intention to blow the whistle again

A systematic review and meta-analysis of the effects of clinical pathways on length of stay, hospital costs and patient outcomes

Background. To perform a systematic review about the effect of using clinical pathways on length of stay (LOS), hospital costs and patient outcomes. To provide a framework for local healthcare organisations considering the effectiveness of clinical pathways as a patient management strategy. Methods. As participants, we considered hospitalized children and adults of every age and indication whose treatment involved the management strategy "clinical pathways". We include only randomised controlled trials (RCT) and controlled clinical trials (CCT), not restricted by language or country of publication. Single measures of continuous and dichotomous study outcomes were extracted from each study. Separate analyses were done in order to compare effects of clinical pathways on length of stay (LOS), hospital costs and patient outcomes. A random effects meta-analysis was performed with untransformed and log transformed outcomes. Results. In total 17 trials met inclusion criteria, representing 4,070 patients. The quality of the included studies was moderate and studies reporting economic data can be described by a very limited scope of evaluation. In general, the majority of studies reporting economic data (LOS and hospital costs) showed a positive impact. Out of 16 reporting effects on LOS, 12 found significant shortening. Furthermore, in a subgroup-analysis, clinical pathways for invasive procedures showed a stronger LOS reduction (weighted mean difference (WMD) -2.5 days versus -0.8 days)). There was no evidence of differences in readmission to hospitals or in-hospital complications. The overall Odds Ratio (OR) for re-admission was 1.1 (95% CI: 0.57 to 2.08) and for in-hospital complications, the overall OR was 0.7 (95% CI: 0.49 to 1.0). Six studies examined costs, and four showed significantly lower costs for the pathway group. However, heterogeneity between studies reporting on LOS and cost effects was substantial. Conclusion. As a result of the relatively small number of studies meeting inclusion criteria, this evidence base is not conclusive enough to provide a replicable framework for all pathway strategies. Considering the clinical areas for implementation, clinical pathways seem to be effective especially for invasive care. When implementing clinical pathways, the decision makers need to consider the benefits and costs under different circumstances (e.g. market forces)

Recent intimate partner violence as a prenatal predictor of maternal depression in the first year postpartum among Latinas

The study aims to determine if recent intimate partner violence (IPV) is a prenatal risk factor for postpartum depression (PPD) among pregnant Latinas seeking prenatal care. A prospective observational study followed Latinas from pregnancy through 13 months postpartum. Prenatal predictors of PPD included depression, recent IPV exposure, remote IPV exposure, non-IPV trauma history, poverty, low social support, acculturation, high parity, and low education. Postpartum depression was measured at 3, 7, and 13 months after birth with the Beck's Depression Inventory—Fast Screen. Strength of association was evaluated using bivariate and multivariable odds ratio analysis. Subjects were predominantly low income, monolingual Spanish, and foreign-born, with mean age of 27.7. Recent IPV, prenatal depression, non-IPV trauma, and low social support were associated with greater likelihood of PPD in bivariate analyses. Recent IPV and prenatal depression continued to show significant association with PPD in multivariate analyses, with greater odds of PPD associated with recent IPV than with prenatal depression (adjusted OR = 5.38, p < 0.0001 for recent IPV and adjusted OR = 3.48, p< 0.0001 for prenatal depression). Recent IPV exposure is a strong, independent prenatal predictor of PPD among Latinas. Screening and referral for both IPV and PPD during pregnancy may help reduce postpartum mental health morbidity among Latinas

“It was Pretty Scary”: The Theme of Fear in Young Adult Women's Descriptions of a History of Adolescent Dating Abuse

The mental health impact of abusive adolescent dating relationships has not been well described, but fear related to abuse has been reported. We elaborate the theme of fear in women's descriptions of a history of adolescent dating abuse. A sample of community-based women, ages 19-34, who experienced an abusive dating relationship during adolescence (ages 11-20) was used. Data were analyzed via thematic analysis. Fear was a consistent and resonant theme. Three types of fear were identified: fear for self, fear for other relationships, and fearful expectation. These results offer important insights into the impact of abusive adolescent relationships on women's mental health