Termination Of Programs Research Articles

Synthesis of models for order-sorted first-order theories using linear algebra and constraint solving

Recent developments in termination analysis for declarative programs emphasize the use of appropriate models for the logical theory representing the program at stake as a generic approach to prove termination of declarative programs. In this setting, Order-Sorted First-Order Logic provides a powerful framework to represent declarative programs. It also provides a target logic to obtain models for other logics via transformations. We investigate the automatic generation of numerical models for order-sorted first-order logics and its use in program analysis, in particular in termination analysis of declarative programs. We use convex domains to give domains to the different sorts of an order-sorted signature; we interpret the ranked symbols of sorted signatures by means of appropriately adapted convex matrix interpretations. Such numerical interpretations permit the use of existing algorithms and tools from linear algebra and arithmetic constraint solving to synthesize the models.

VPHL: A Verified Partial-Correctness Logic for Probabilistic Programs

We introduce a Hoare-style logic for probabilistic programs, called VPHL, that has been formally verified in the Coq proof assistant. VPHL features propositional, rather than additive, assertions and a simple set of rules for reasoning about these assertions using the standard axioms of probability theory. VPHL's assertions are partial correctness assertions, meaning that their conclusions are dependent upon (deterministic) program termination. The underlying simple probabilistic imperative language, PrImp, includes a probabilistic toss operator, probabilistic guards and potentially-non-terminating while loops.

Incentives to using solar thermal energy in Taiwan

Abstract A national subsidy program is one of the key elements for translating customer choice into a larger market share for renewable energies. Since solar water heaters (SWHs) are a cost-effective and mature technology, purchase-based subsidy programs have been sponsored by the Bureau of Energy, Ministry of Economic Affairs (BEMOEA) in Taiwan. The market of SWHs is associated with economic factors, population characteristics, degree of urbanization (available roof space), and climatic conditions. Regional programs have also affected the growth in sales. However, the penetration rates are still low, and the local market has changed little in recent years. Thus, the timing of the termination of the long-duration subsidy program is a subject of debate. In this study, a new scheme in the residential sector is proposed in the period of 2016 to 2019. In addition, small and medium enterprises (SMEs) make up the majority of Taiwanese companies. Most SMEs suffer from insufficient capital to support their commercial activities. To prompt solar thermal energy in the commercial sector, the energy service company (ESCO) business model can be adopted. The same feed-in tariffs for PV systems can be granted for SWHs and photovoltaic/thermal (PVT) systems with performance-based subsidies to end users or ESCOs.

Abstract Book

Major control efforts over many decades have resulted in a substantial reduction in the prevalence of schistosomiasis japonica in the People’s Republic of China, although pockets of new infection continue to arise, particularly in the mountainous areas of the south. As well, the completion of the Three Gorges Dam, which crosses the Yangtze River and other large irrigation projects underway, may have significant environmental and ecological impacts likely resulting in expansion of the habitats for the intermediate snail host Oncomelania hupensis in some areas, thereby increasing the risk of human and bovine infection, and resulting in potentially new challenging consequences for control. The epidemiological picture for China will be briefly summarised and the current effective control strategies highlighted. The situation in the Philippines will also be briefly outlined but the picture is far less encouraging as there is limited national funding for schistosomiasis control; since the termination of the World Bank Loan program for schistosomiasis control in the late 1990’s, both schistosome prevalence and the associated morbidity have rebounded to former levels. Some results of recent surveillance studies we have undertaken in the Philippines will be described which indicate that schistosomiasis japonica is now far more prevalent, both in humans and bovines, than has been appreciated. Results of a large intervention trial we have completed in China - in the highly endemic Dongting Lake area downstream of the Three Gorges Dam, aimed at field-testing integrated strategies, including the use of a bovine transmission blocking vaccine, for schistosomiasis control, will be presented. The results of the trial in China will provide parameters for mathematical modelling of future control methods so as to define the long-term impact and cost-effectiveness of integrated control measures for both China and the Philippines. We believe that such an integrated approach, incorporating bovine vaccination, can lead to the future elimination of schistosomiasis from China.

Physical activity in anorexia nervosa: How relevant is it to therapy response?

ObjectiveElevated physical activity has been observed in some patients with anorexia nervosa (AN) despite their emaciated condition. However, its effects on treatment outcome remain unclear. This study aimed to examine objectively measured physical activity in this clinical population and how it might be related to a partial hospitalization therapy response, after considering potential confounders. MethodThe sample comprised 88 AN patients consecutively enrolled in a day hospital treatment program, and 116 healthy-weight controls. All participants were female and a baseline assessment took place using an accelerometer (Actiwatch AW7) to measure physical activity, the Eating Disorders Inventory-2 and the Depression subscale of the Symptom Checklist-Revised. Outcome was evaluated upon the termination of the treatment program by expert clinicians. ResultsAlthough AN patients and controls did not differ in the average time spent in moderate-to-vigorous physical activity (MVPA) (P=.21), nor daytime physical activity (P=.34), fewer AN patients presented a high physical activity profile compared to the controls (37% vs. 61%, respectively; P=.014). Both lower levels of MVPA and greater eating disorder severity had a direct effect on a poor treatment outcome. Depression symptoms in the patients were associated with lower MVPA, as well as with an older age, a shorter duration of the disorder and greater eating disorder psychopathology. ConclusionsThere is a notable variation in the physical activity profile of AN patients, characterized by either low or very high patterns. Physical activity is a highly relevant issue in AN that must be taken into account during the treatment process.

Factors Supporting or Hindering Continuation of a Collaborative Professional Development Program for Communicative Language Teaching

In this study, the continued use of core elements of a collaborative professional development program (CPDP) for communicative language teaching (CLT) after program termination is reported. A cross-sectional design using quantitative and qualitative data collection was applied. Teachers, facilitators and management perceived CPDP relevant and teachers appreciated the program elements. Teachers who participated in the development and implementation sessions of CPDP tended to apply CPDP elements better than teachers who merely used CPDP elements. Teacher collaboration was limited. Facilitators and management offered little support for teachers after the termination of the CPDP. The study recommended embedding CPDP in the English language department system as an in-service professional development program.

Impact of aerobic and resistance exercise combination on physical self-perceptions and self-esteem in women with obesity with one-year follow-up

The effectiveness of an exercise intervention including both aerobics and resistance training components in improving physical self-perceptions and global self-esteem (GSE) in women with obesity was examined. An experimental design with a one-year follow-up was used. Women with obesity (n = 72) participated in a structured exercise programme for 12 weeks after being randomised into a control and an exercise group. Exercise self-efficacy, body attractiveness, physical strength, sport competence, physical condition, physical self-worth, and GSE were measured at pre-intervention, early intervention, mid-intervention, immediately after the intervention, and five times following programme termination at 1, 3, 6, 9, and 12 months, respectively. Analyses of covariance revealed exercise effects for all of the dependent variables except for body attractiveness. Generally, exercise effects lasted between 6 and 12 months. A 12-week physical exercise programme including aerobic and resistance training components has the potential to improve physical self-perceptions and self-esteem in women with obesity.

An intuitionistic version of Ramsey's Theorem and its use in Program Termination

Ramsey's Theorem for pairs is a fundamental result in combinatorics which cannot be intuitionistically proved. In this paper we present a new form of Ramsey's Theorem for pairs we call the H-closure Theorem, where H stands for “homogeneous”. The H-closure Theorem is a property of well-founded relations, intuitionistically provable, informative, and simple to use in intuitionistic proofs. Using our intuitionistic version of Ramsey's Theorem we intuitionistically prove the Termination Theorem by Podelski and Rybalchenko [25]. The Termination Theorem concerns an algorithm inferring termination for while-programs, and was originally proved from the classical Ramsey Theorem. Vytiniotis, Coquand, and Wahlstedt provided an intuitionistic proof of the Termination Theorem [29], using the Almost Full Theorem [11], an intuitionistic version of Ramsey's Theorem different from the H-closure Theorem. We provide a second intuitionistic proof of the Termination Theorem using the H-closure Theorem. In another paper, we use our proof to extract bounds for the Termination Theorem [5].

The highs and lows of a cultural transition: a longitudinal analysis of sojourner stress and adaptation across 50 countries.

The impact of living abroad is a topic that has intrigued researchers for almost a century, if not longer. While many acculturation phenomena have been studied over this time, the development of new research methods and statistical software in recent years means that these can be revisited and examined in a more rigorous manner. In the present study we were able to follow approximately 2,500 intercultural exchange students situated in over 50 different countries worldwide, over time both before and during their travel using online surveys. Advanced statistical analyses were employed to examine the course of sojourners stress and adjustment over time, its antecedents and consequences. By comparing a sojourner sample with a control group of nonsojourning peers we were able to highlight the uniqueness of the sojourn experience in terms of stress variability over time. Using Latent Class Growth Analysis to examine the nature of this variability revealed 5 distinct patterns of change in stress experienced by sojourners over the course of their exchange: a reverse J-curve, inverse U-curve, mild stress, minor relief, and resilience pattern. Antecedent explanatory variables for stress variability were examined using both variable-centered and person-centered analyses and evidence for the role of personality, empathy, cultural adaptation, and coping strategies was found in each case. Lastly, we examined the relationship between stress abroad with behavioral indicators of (mal)adjustment: number of family changes and early termination of the exchange program.

Challenges and solutions in the bioanalysis of BMS-986094 and its metabolites including a highly polar, active nucleoside triphosphate in plasma and tissues using LC-MS/MS.

BMS-986094, a nucleotide polymerase inhibitor of the hepatitis C virus, was withdrawn from clinical trials because of a serious safety issue. To investigate a potential association between drug/metabolite exposure and toxicity in evaluations conducted after the termination of the BMS-986094 development program, it was essential to determine the levels of BMS-986094 and its major metabolites INX-08032, INX-08144 and INX-09054 in circulation and the active nucleoside triphosphate INX-09114 in target and non-target tissues. However, there were many challenges in the bioanalysis of these compounds. The chromatography challenge for the extremely polar nucleoside triphosphate was solved by applying mixed-mode chromatography which combined anion exchange and reversed-phase interactions. The LC conditions provided adequate retention and good peak shape of the analyte and showed good robustness. A strategy using simultaneous extraction but separate LC analysis of the prodrug BMS-986094 and its major circulating metabolites was used to overcome a carryover issue of the hydrophobic prodrug while still achieving good chromatography of the polar metabolites. In addition, the nucleotide analytes were not stable in the presence of endogenous enzymes. Low pH and low temperature were required for blood collection and plasma sample processing. However, the use of phosphatase inhibitor and immediate homogenization and extraction were critical for the quantitative analysis of the active triphosphate, INX-09114, in tissue samples. To alleviate the bioanalytical complexity caused by multiple analytes, different matrices, and various species, a fit-for-purpose approach to assay validation was implemented based on the needs of drug safety assessment in non-clinical (GLP or non-GLP) studies. The assay for INX-08032 was fully validated in plasma of toxicology species. The lower limit of quantification was 1.00ng/mL and the linear curve range was 1.00-500.00ng/mL using a weighted (1/x(2)) linear regression model. Intra-assay and inter-assay precision (CV, %) ranged from 2.3% to 5.5% and accuracy within ±2.2% from nominal. INX-08032 was found to be stable in acidified mouse plasma for at least 24h in wet ice bath, 125 days at -70°C and following at least three freeze-thaw cycles. No endogenous components in plasma were found to interfere with the measurement. The extraction recovery was between 90% and 95%. The assays for BMS-986094, INX-08144, INX-09054 and INX-09114 were qualified with wider acceptance criteria for accuracy and precision. Analyte stability was also evaluated to guide sample collection, storage, and processing. These assays were successfully applied to an investigative toxicokinetic and tissue metabolite profiling study described in the article.

Termination and non-termination specification inference

Techniques for proving termination and non-termination of imperative programs are usually considered as orthogonal mechanisms. In this paper, we propose a novel mechanism that analyzes and proves both program termination and non-termination at the same time. We first introduce the concept of second-order termination constraints and accumulate a set of relational assumptions on them via a Hoare-style verification. We then solve these assumptions with case analysis to determine the (conditional) termination and non- termination scenarios expressed in some specification logic form. In contrast to current approaches, our technique can construct a summary of terminating and non-terminating behaviors for each method. This enables modularity and reuse for our termination and non-termination proving processes. We have tested our tool on sample programs from a recent termination competition, and compared favorably against state-of-the-art termination analyzers.

Symbolic execution as a basis for termination analysis

Program termination is a relevant property that has been extensively studied in the context of many different formalisms and programming languages. Traditional approaches to proving termination are usually based on inspecting the source code. Recently, a new semantics-based approach has emerged, which typically follows a two-stage scheme: first, a finite data structure representing the computation space of the program is built; then, termination is analyzed by inspecting the transitions in this data structure using traditional, syntax-based techniques.Unfortunately, this approach is still specific to a programming language and semantics. In this work, we present instead a general, high-level framework that follows the semantics-based approach to proving termination. In particular, we focus on the first stage and advocate the use of symbolic execution, together with appropriate subsumption and abstraction operators, for producing a finite representation of the computations of a program. Hopefully, this higher level approach will provide useful insights for designing new semantics-based termination tools for particular programming languages.

Probabilistic Termination

We propose a framework to prove almost sure termination for probabilistic programs with real valued variables. It is based on ranking supermartingales, a notion analogous to ranking functions on non-probabilistic programs. The framework is proven sound and complete for a meaningful class of programs involving randomization and bounded nondeterminism. We complement this foundational insigh by a practical proof methodology, based on sound conditions that enable compositional reasoning and are amenable to a direct implementation using modern theorem provers. This is integrated in a small dependent type system, to overcome the problem that lexicographic ranking functions fail when combined with randomization. Among others, this compositional methodology enables the verification of probabilistic programs outside the complete class that admits ranking supermartingales.

Sources for Leads: Natural Products and Libraries.

Natural products have traditionally been a major source of leads in the drug discovery process. However, the development of high-throughput screening led to an increased interest in synthetic methods that enabled the rapid construction of large libraries of molecules. This resulted in the termination or downscaling of many natural product research programs, but the chemical libraries did not necessarily produce a larger amount of drug leads. On one hand, this chapter explores the current state of natural product research within the drug discovery process. On the other hand it evaluates the efforts made to increase the amount of leads generated from chemical libraries and considers what role natural products could play here.

Abstract 13261: Determining the Cost-Benefit Yields of Participating in a Cardiac Rehabilitation Program

Background and Objective: Regular participation in cardiac rehabilitation (CR) has been consistently shown to improve survival prognosis for patients suffering from a recent cardiovascular episode. No study has quantified the thresholds of baseline risk/behavioral attrition beyond which the cost-benefits of CR become economically unattractive. We aimed to determine how the cost-benefits associated with CR vary across baseline risk and behavioral attrition patterns amongst an actual population of patients participating in an outpatient CR program. Methods: Data was obtained from 11,998 consecutive patient referrals to Toronto Rehab Cardiac Rehabilitation and Secondary Prevention Program (1995 to 2010). Baseline risk was defined as the probability of death/hospitalization at 2 years following program termination and behavioral attrition as the probability of program drop-out. We assumed a fixed cost of $1500 per program and a fixed program efficacy of 20% reduction in death/hospitalization. Multiple logistic regression models were used to predict the number of deaths/hospitalizations avoided per 1000 patients treated. Results: Regression models for baseline risk and baseline behavioral attrition produced C-statistics of 0.66 and 0.85, respectively. Increasing age, type 2 diabetes were found to be concordant predictors of CR cost-benefit and higher baseline functional capacity as a discordant predictor. The correlation between program drop out risk and baseline risk was poor (r=0.22, p<0.001). There was a 13% increased risk of predicted dropout for each quartile of program cost to yield (RR 0.87, 95% CI: 0.87, 0.89), while for each 10% baseline risk increase, RR was found to be 1.36 (95% CI: 1.34, 1.37). For both risk factors as predictors of improved cost-benefit yield ($1000 cost per adverse-event avoided) there was a 21% higher likelihood of the program being economically attractive for each 10% increase in behavioral attrition risk (RR 1.21, 95% CI: 1.207, 1.213). Conclusion: Baseline risk and behavioral attrition are important determinants of CR effectiveness and underscores the potential utility of risk stratification and patient baseline/behavioral attrition risk thresholds to estimate the programmatic benefit of CR programs.

Trans Fatty acids in the Canadian food supply: an updated analysis

Dietary trans fatty acids (TFAs) increase the risk of heart disease. In 2007, Canada set voluntary TFA limits for industrial TFAs added to food and encouraged substitution of TFAs with unsaturated fats during reformulation. No longitudinal follow-up assessment of TFA amounts in foods has occurred in Canada since termination of a government-led Trans Fat Monitoring Program (TFMP). The objective was to conduct an updated assessment and longitudinally evaluate TFA amounts in the food supply and to determine whether saturated fats have replaced TFAs in reformulation. This was a cross-sectional study that used 3 databases: TFMP (Health Canada, 2005-2009; n = 921), the University of Toronto Food Label Information Program (2010-2011; n = 5544), and the Restaurant Database (2010; n = 4272). Outcomes were TFAs as a percentage of fat, proportion of foods meeting TFA limits, and saturated fat amounts in foods with high or low TFAs. The proportion of foods meeting TFA limits improved from 75% in 2005-2009 to 97% in 2010-2011, particularly in the following packaged foods: croissants (25% to 100%), pies (36% to 98%), cakes (43% to 90%), and garlic spreads (33% to 100%). Most restaurant categories assessed by the TFMP had 100% of foods meeting TFA limits. Some categories had a large proportion that exceeded TFA limits: dairy-free cheeses (100%), frosting (72.0%), lard and shortening (66.7%), coffee whiteners (66.7%), and restaurant-prepared biscuits and scones (47.4%). Saturated fat amounts were significantly higher (P < 0.05) among some foods with the lowest TFAs, such as cookies, brownies and squares, cakes with pudding/mousse, dessert toppings, and lard and shortening. There has been an impressive improvement in TFA amounts in the Canadian food supply since the termination of the TFMP. However, action by the food industry is required to reduce TFAs in foods that exceed the recommended TFA limits and to minimize the use of saturated fats in replacing TFAs during reformulation.

The effect of the rural tourism policy on non-farm income in South Korea

There has been growing concern as to whether the growing investment in rural South Korea is achieving the desired ends. Empirical evidence is required to assess the current policies. Based on the logic of those policies, this study conducts an ex-post evaluation of outcomes following the termination of the Rural Traditional Theme Village program previously operated by the Rural Development Administration, a central government agency in South Korea. The research adopts farm households' non-farm income as an ex-post quantifiable indicator and assesses the impact of the Program on this indicator. It is found that the Program was evaluated positively and as being effective from both cross-sectional and longitudinal perspectives. It is concluded that in the absence of the program the farms would have experienced difficulties in making non-farm income due to the lack of internal competitiveness and the deterioration of human resources.

Termination of Linear Programs: Advances and Challenges

Termination of Linear Programs: Advances and Challenges

Checking termination of bottom-up evaluation of logic programs with function symbols

AbstractRecently, there has been an increasing interest in the bottom-up evaluation of the semantics of logic programs with complex terms. The presence of function symbols in the program may render the ground instantiation infinite, and finiteness of models and termination of the evaluation procedure, in the general case, are not guaranteed anymore. Since the program termination problem is undecidable in the general case, several decidable criteria (called program termination criteria) have been recently proposed. However, current conditions are not able to identify even simple programs, whose bottom-up execution always terminates. The paper introduces new decidable criteria for checking termination of logic programs with function symbols under bottom-up evaluation, by deeply analyzing the program structure. First, we analyze the propagation of complex terms among arguments by means of the extended version of the argument graph calledpropagation graph. The resulting criterion, calledacyclicity, generalizes most of the decidable criteria proposed so far. Next, we study how rules may activate each other and define a more powerful criterion, calledsafety. This criterion uses the so-calledsafety functionable to analyze how rules may activate each other and how the presence of some arguments in a rule limits its activation. We also study the application of the proposed criteria to bound queries and show that the safety criterion is well-suited to identify relevant classes of programs and bound queries. Finally, we propose a hierarchy of classes of terminating programs, calledk-safety, where thek-safe class strictly includes the (k-1)-safe class.

Efficient Solution of a Class of Quantified Constraints with Quantifier Prefix Exists-Forall

In various applications the search for certificates for certain properties (e.g., stability of dynamical systems, program termination) can be formulated as a quantified constraint solving problem with quantifier prefix exists-forall. In this paper, we present an algorithm for solving a certain class of such problems based on interval techniques in combination with conservative linear programming approximation. In comparison with previous work, the method is more general—allowing general Boolean structure in the input constraint, and more efficient—using splitting heuristics that learn from the success of previous linear programming approximations.