The double of the doubles of Klein surfaces

A Klein surface is a surface with a dianalytic structure. A double of a Klein surface $X$ is a Klein surface $Y$ such that there is a degree two morphism (of Klein surfaces) $Y\rightarrow X$. There are many doubles of a given Klein surface and among them the so-called natural doubles which are: the complex double, the Schottky double and the orienting double. We prove that if $X$ is a non-orientable Klein surface with non-empty boundary, the three natural doubles, although distinct Klein surfaces, share a common double: "the double of doubles" denoted by $DX$. We describe how to use the double of doubles in the study of both moduli spaces and automorphisms of Klein surfaces. Furthermore, we show that the morphism from $DX$ to $X$ is not given by the action of an isometry group on classical surfaces.Comment: 14 pages; more details in the proof of theorem

Investigating Automatic Static Analysis Results to Identify Quality Problems: an Inductive Study

Background: Automatic static analysis (ASA) tools examine source code to discover "issues", i.e. code patterns that are symptoms of bad programming practices and that can lead to defective behavior. Studies in the literature have shown that these tools find defects earlier than other verification activities, but they produce a substantial number of false positive warnings. For this reason, an alternative approach is to use the set of ASA issues to identify defect prone files and components rather than focusing on the individual issues. Aim: We conducted an exploratory study to investigate whether ASA issues can be used as early indicators of faulty files and components and, for the first time, whether they point to a decay of specific software quality attributes, such as maintainability or functionality. Our aim is to understand the critical parameters and feasibility of such an approach to feed into future research on more specific quality and defect prediction models. Method: We analyzed an industrial C# web application using the Resharper ASA tool and explored if significant correlations exist in such a data set. Results: We found promising results when predicting defect-prone files. A set of specific Resharper categories are better indicators of faulty files than common software metrics or the collection of issues of all issue categories, and these categories correlate to different software quality attributes. Conclusions: Our advice for future research is to perform analysis on file rather component level and to evaluate the generalizability of categories. We also recommend using larger datasets as we learned that data sparseness can lead to challenges in the proposed analysis proces

Pavlovian Processes in Consumer Choice: The Physical Presence of a Good Increases Willingness-to-Pay

This paper describes a series of laboratory experiments studying whether the form in which items are displayed at the time of decision affects the dollar value that subjects place on them. Using a Becker-DeGroot auction under three different conditions — (i) text displays, (ii) image displays, and (iii) displays of the actual items — we find that subjects' willingness-to-pay is 40-61 percent larger in the real than in the image and text displays. Furthermore, follow-up experiments suggest the presence of the real item triggers preprogrammed consummatory Pavlovian processes that promote behaviors that lead to contact with appetitive items whenever they are available

Revenue-Recycling and the Efficiency and Spatial Distributional Impacts of Development Taxes

Recent studies that compare the efficiency and distributional impacts of alternative instruments to curb sprawl typically ignore what to do with the revenues from anti-sprawl policies, such as development taxes. This paper extends first-best analysis of development taxes aimed at preserving land at the urban fringe to account for interactions with other distortions within the urban system. By incorporating urban decline at the city core, which in turn, generates negative neighborhood spillover effects and extra pressure for development at the urban fringe, we provide a more complete framework to evaluate the efficiency and distributional impacts of development taxes. We consider three potential alternative schemes to recycle the revenues: lump sum recycling, earmarked revenues to purchase conservation easements that permanently save open space and earmarked revenues to subsidize a revitalization program at the city core. In this setting, when revenues from the development tax are earmarked to fund a conservation easement there is an additional welfare gain (relative to the lump sum case) because the threat of future conversation of open space is fully eliminated. Similarly, when revenues are earmarked to fund a revitalization program at the city core, there are additional sources of welfare that make this policy preferred relative to the lump-sum recycling scheme. Finally, we also explore the spatial distributional impacts of these three alternative recycling schemes.Urban Sprawl, Revenue-Recycling, Regional Coordination, Spatial Modeling, Environmental Economics and Policy, Land Economics/Use, Resource /Energy Economics and Policy, Q31, R14, R38,

Welfare Effects of Anti-Sprawl Policies in the Presence of Urban Decline

This paper extends first-best analysis of anti-sprawl policies, such as development taxes, and examines the welfare effects of development taxes in the presence of urban decline at the city core. We find that anti-sprawl policies generate several important feedbacks within the urban system, generating additional welfare gains and affecting the level of urban decline and suburban sprawl. Further, the optimal development tax exceeds the (first-best) Pigouvian level, irrespective of whether or not revenues are returned lump-sum to all landowners or earmarked for urban decline mitigation.urban sprawl, development taxes, second-best policies, spatial modeling, Land Economics/Use,