Regular realizability problems and context-free languages

We investigate regular realizability (RR) problems, which are the problems of verifying whether intersection of a regular language -- the input of the problem -- and fixed language called filter is non-empty. In this paper we focus on the case of context-free filters. Algorithmic complexity of the RR problem is a very coarse measure of context-free languages complexity. This characteristic is compatible with rational dominance. We present examples of P-complete RR problems as well as examples of RR problems in the class NL. Also we discuss RR problems with context-free filters that might have intermediate complexity. Possible candidates are the languages with polynomially bounded rational indices.Comment: conference DCFS 201

Locally Chain-Parsable Languages

If a context-free language enjoys the local parsability property then, no matter how the source string is segmented, each segment can be parsed in- dependently, and an efficient parallel parsing algorithm becomes possible. The new class of locally chain-parsable languages (LCPL), included in deterministic context-free languages, is here defined by means of the chain-driven automa- ton and characterized by decidable properties of grammar derivations. Such au- tomaton decides to reduce or not a factor in a way purely driven by the terminal characters, thus extending the well-known concept of Input-Driven (ID) (visibly) pushdown machines. LCPL extend and improve the practically relevant operator- precedence languages (Floyd), which are known to strictly include the ID lan- guages, and for which a parallel-parser generator exists. Consistently with the classical results for ID, chain-compatible LCPL are closed under reversal and Boolean operations, and language inclusion is decidable

Subnational climate entrepreneurship: innovative climate action in California and São Paulo

The distinct role of subnational governments such as states and provinces in addressing climate change has been increasingly acknowledged. But while most studies investigate the causes and consequences of particular governments’ actions and networking activities, this article argues that subnational governments can develop climate action as a collective entrepreneurial activity. Addressing many elements explored in this special issue, it focuses on the second question and identifies climate entrepreneurship in two subnational governments—the states of California (USA) and São Paulo (Brazil). Examining internal action, as well as interaction with local authorities, national governments and the international regime, entrepreneurial activities are identified in the invention, diffusion and evaluation of subnational climate policy in each case. The article draws from the recent scholarship on policy innovation, entrepreneurship and climate governance. It contributes to the literature by exploring entrepreneurial subnational government activity in addressing climate change and expanding the understanding of the effects of policy innovation at the subnational level

Efecto del cribado social sobre la eficiencia de los fondos: evidencia empírica de los fondos de renta variable europeos

ABSTRACT: The aim of this study is to evaluate the financial performance of European socially responsible investment (SRI) funds for the period 1993–2012 to contrast whether there is a relationship between the application of social screening on investment decisions and funds’ financial performance measured by Carhart’s alpha. Regression analysis has been used to test the hypotheses of this research with a sample free of survivorship bias of 184 SRI equity funds from 14 European countries and the population of conventional funds from the same country and investment objective. The main conclusion of this study is that the application of social criteria in investment decisions carries a cost to the investor in terms of lower financial performance caused by differences in screening intensity.RESUMEN: El objetivo de este trabajo es evaluar la eficiencia financiera de los fondos socialmente responsables europeos durante el periodo 1993–2012 a fin de contrastar si existe una relación entre la aplicación del cribado social en las decisiones de inversión y la eficiencia financiera del fondo medida con el alfa de Carhart. El análisis de regresión ha sido empleado para contrastar las hipótesis de esta investigación con una muestra libre de sesgo de supervivencia de 184 fondos sociales de renta variable de 14 países europeos y la población de fondos convencionales del mismo país y objetivo de inversión. La principal conclusión de este estudio es que la aplicación de criterios sociales en las decisiones de inversión conlleva un coste para el inversor en términos de una menor eficiencia financiera causada por diferencias en la intensidad del cribado social