Beating the Productivity Checker Using Embedded Languages

Some total languages, like Agda and Coq, allow the use of guarded corecursion to construct infinite values and proofs. Guarded corecursion is a form of recursion in which arbitrary recursive calls are allowed, as long as they are guarded by a coinductive constructor. Guardedness ensures that programs are productive, i.e. that every finite prefix of an infinite value can be computed in finite time. However, many productive programs are not guarded, and it can be nontrivial to put them in guarded form. This paper gives a method for turning a productive program into a guarded program. The method amounts to defining a problem-specific language as a data type, writing the program in the problem-specific language, and writing a guarded interpreter for this language.Comment: In Proceedings PAR 2010, arXiv:1012.455

Real and nominal wage adjustment in open economies

How are wages set in an open economy? What role is played by demand pressure, international competition, and structural factors in the labour market? How important is nominal wage rigidity and exchange rate policy for the medium term evolution of real wages and competitiveness? To answer these questions, we formulate a theoretical model of wage bargaining in an open economy and use it to derive a simple wage equation where all parameters have clear economic interpretations. We estimate the wage equation on data for aggregate manufacturing wages in Denmark, Finland, Norway, and Sweden from the mid 1960s to the mid 1990s.Wage formation; efficiency wage; turnover; bargaining; rent sharing; nominal wage rigidity; exchange rate policy; competitiveness

Real and Nominal Wage Adjustment in Open Economies

How are wages set in an open economy? What role is played by demand pressure, international competition, and structural factors in the labour market? How important is nominal wage rigidity and exchange rate policy for the evolution of real wages and competitiveness? To answer these questions, we formulate a theoretical model of wage bargaining in an open economy and use it to derive a simple wage equation where all parameters have clear economic interpretations. We estimate the wage equation on data for aggregate manufacturing wages in Denmark, Finland, Norway, and Sweden from the mid 1960s to the mid 1990s.wage formation, efficiency wage, turnover, bargaining, rent sharing, nominal wage rigidity, exchange rate policy, competitiveness

The Interaction Between Religiosity and Depression Among Students at Two Universities

The association between religion and mental health has been a long standing topic of the debate. Some have felt that religion leads to emotional and mental disturbances and thus is detrimental to mental health (Freud, 1907/1924, 1927/1961; Ellis, 1980, 1988); while others believe religion is helpful to mental health (Jung, 1932, 1933; Bergin 1980, 1983) . This study used 180 male and female (79%) college students from a Midwestern state university (62%) and a Christian liberal arts college. It was found that for women, private religiosity was negatively related to depression, as measured by the BDI. Students from the state university were more likely to be depressed than those from the Christian college. In addition, BDI score was predicted by being a lower income student from the state university

The Interaction Between Religiosity and Depression Among Students at Two Universities

The association between religion and mental health has been a long standing topic of the debate. Some have felt that religion leads to emotional and mental disturbances and thus is detrimental to mental health (Freud, 1907/1924, 1927/1961; Ellis, 1980, 1988); while others believe religion is helpful to mental health (Jung, 1932, 1933; Bergin 1980, 1983) . This study used 180 male and female (79%) college students from a Midwestern state university (62%) and a Christian liberal arts college. It was found that for women, private religiosity was negatively related to depression, as measured by the BDI. Students from the state university were more likely to be depressed than those from the Christian college. In addition, BDI score was predicted by being a lower income student from the state university

The Bioeconomics of Controlling an African Rodent Pest Species

The paper treats the economy of controlling an African pest rodent, the multimammate rat, causing major damage in maize production. An ecological population model is presented and used as a basis for the economic analyses carried out at the village level using data from Tanzania. This model incorporates both density-dependent and density-independent (stochastic) factors. Rodents are controlled by applying poison, and the economic benefits depend on the income from maize production minus the costs for maize production, fertiliser and poison. We analyse how the net present value of maize production is affected by various rodent control strategies, by varying the duration and timing of rodenticide application. Our numerical results suggest that, in association with fertiliser, it is economically beneficial to control the rodent population. In general the most rewarding duration of controlling the rodent population is 3-4 months every year, and especially at the end of the dry season/beginning of rainy season. The paper demonstrates that changing from todays practice of symptomatic treatment when heavy rodent damage is noticed to a practice where the calendar is emphasised, may substantially improve the economic conditions for the maize producing farmers. This main conclusion is quite robust and not much affected by changing prices and costs of the maize production.bio-economics; pest control; multimammate rat; crop production

Invading herbivory: The golden apple snail alters ecosystem functioning in Asian wetlands

We investigated the effects of an exotic snail, the golden apple snail (Pomacea canaliculata) on biodiversity and ecosystem functioning in tropical wetland ecosystems. This large snail (up to 80-mm shell height) has invaded large parts of Southeast Asia during recent decades. A survey of natural wetlands in Thailand showed that high densities of the snail were associated with almost complete absence of aquatic plants, high nutrient concentrations, and high phytoplankton biomass, that is, a complete shift in both ecosystem state and function. A field experiment demonstrated that grazing by the snail can cause the loss of aquatic plants, a change toward dominance of planktonic algae, and thereby a shift toward turbid water. Estimates of biologically fixed nutrients released through snails grazing on aquatic plants revealed that phosphorus releases were sufficient to explain the recorded increase in phytoplankton biomass. Hence, our study demonstrates how an herbivore may trigger a shift from clear water and macrophyte dominance to a turbid state dominated by planktonic algae. This shift and the continuing aggressive invasion of this exotic species are detrimental to the integrity and functioning of wetland ecosystems, and to the services these provide in Southeast Asia

The DSD Schema Language and its Applications

XML (eXtensible Markup Language), a linear syntax for trees, has gathered a remarkable amount of interest in industry. The acceptance of XML opens new venues for the application of formal methods such as specification of abstract syntax tree sets and tree transformations. A user domain may be specified as a set of trees. For example, XHTML is a user domain corresponding to the set of XML documents that make sense asHTML. A notation for defining such a set of XML trees is called a schema language. We believe that a useful schema notation must identify most of the syntacticrequirements that the documents in the user domain follow; allow efficient parsing; be readable to the user; allow a declarative default notation `a la CSS; and bemodular and extensible to support evolving classes of XML documents. In the present paper, we give a tutorial introduction to the DSD (Document Structure Description) notation as our bid on how to meet these requirements. TheDSD notation was inspired by industrial needs, and we show how DSDs help manage aspects of complex XML software through a case study about interactive voiceresponse systems (automated telephone answering systems, where input is through the telephone keypad or speech recognition). The expressiveness of DSDs goes beyond the DTD schema concept that is alreadypart of XML. We advocate the use of nonterminals in a top-down manner, coupled with boolean logic and regular expressions to describe how constraints on tree nodes depend on their context. We also support a general, declarative mechanism for inserting default elements and attributes that is reminiscent of CascadingStyle Sheets (CSS), a way of manipulating formatting instructions in HTML that is built into all modern browsers. Finally, we include a simple technique for evolving DSDs through selective redefinitions. DSDs are in many ways much more expressive than XML Schema (the schema language proposed by the W3C), but their syntactic and semantic definition in English is only 1/8th the size. Also, the DSD notation is self-describable: the syntax of legal DSD documents and all static semantic requirements can be captured in a DSD document, called the meta-DSD