Schematic Cut elimination and the Ordered Pigeonhole Principle [Extended Version]

In previous work, an attempt was made to apply the schematic CERES method [8] to a formal proof with an arbitrary number of {\Pi} 2 cuts (a recursive proof encapsulating the infinitary pigeonhole principle) [5]. However the derived schematic refutation for the characteristic clause set of the proof could not be expressed in the formal language provided in [8]. Without this formalization a Herbrand system cannot be algorithmically extracted. In this work, we provide a restriction of the proof found in [5], the ECA-schema (Eventually Constant Assertion), or ordered infinitary pigeonhole principle, whose analysis can be completely carried out in the framework of [8], this is the first time the framework is used for proof analysis. From the refutation of the clause set and a substitution schema we construct a Herbrand system.Comment: Submitted to IJCAR 2016. Will be a reference for Appendix material in that paper. arXiv admin note: substantial text overlap with arXiv:1503.0855

The Crisis And Central Bank Reaction

The world economy is in the face of the strongest crisis of the last seventy years. This crisis is still ongoing, but authorities in many countries have already taken a series of measures to mitigate the effects. In this fight, the central banks are the first line. It is still too early to draw any lessons from the events taking place, but a reflection "sine ira et studio" over this experience is already possible. This paper aims to analyze this experience through the policies implemented by central banks to cope with the crisis.central bank, crisis, liquidity, regulation

Journalism in Second Life

Our research seeks to understand the emerging journalism practiced in Second Life—a computer-generated alternative reality. Framed by postmodernism, this study uses an ideological analysis to evaluate the three Second Life newspapers: the Alphaville Herald, the Metaverse Messenger and the Second Life Newspaper. We suggest that journalism in Second Life focuses on community building and education, considers the influence of the on-line world to resident members\u27 off-line lives and raises important questions about freedom of expression

Junior Recital

List of performers and performances

Finding Regressions in Projects under Version Control Systems

Version Control Systems (VCS) are frequently used to support development of large-scale software projects. A typical VCS repository of a large project can contain various intertwined branches consisting of a large number of commits. If some kind of unwanted behaviour (e.g. a bug in the code) is found in the project, it is desirable to find the commit that introduced it. Such commit is called a regression point. There are two main issues regarding the regression points. First, detecting whether the project after a certain commit is correct can be very expensive as it may include large-scale testing and/or some other forms of verification. It is thus desirable to minimise the number of such queries. Second, there can be several regression points preceding the actual commit; perhaps a bug was introduced in a certain commit, inadvertently fixed several commits later, and then reintroduced in a yet later commit. In order to fix the actual commit it is usually desirable to find the latest regression point. The currently used distributed VCS contain methods for regression identification, see e.g. the git bisect tool. In this paper, we present a new regression identification algorithm that outperforms the current tools by decreasing the number of validity queries. At the same time, our algorithm tends to find the latest regression points which is a feature that is missing in the state-of-the-art algorithms. The paper provides an experimental evaluation of the proposed algorithm and compares it to the state-of-the-art tool git bisect on a real data set

Optimal Control of MDPs with Temporal Logic Constraints

In this paper, we focus on formal synthesis of control policies for finite Markov decision processes with non-negative real-valued costs. We develop an algorithm to automatically generate a policy that guarantees the satisfaction of a correctness specification expressed as a formula of Linear Temporal Logic, while at the same time minimizing the expected average cost between two consecutive satisfactions of a desired property. The existing solutions to this problem are sub-optimal. By leveraging ideas from automata-based model checking and game theory, we provide an optimal solution. We demonstrate the approach on an illustrative example.Comment: Technical report accompanying the CDC 2013 pape

Boosting College Success Among Men of Color

This brief catalogues strategies commonly used in interventions at postsecondary educational institutions aimed at improving outcomes for male students of color and charts the way forward for future evaluative work. While young men of color have college and career aspirations similar to those of their white counterparts, a significant gap persists between the two groups' postsecondary educational attainment. In response, colleges around the country have implemented targeted programs offering male students of color a variety of support services, yet few of these initiatives have been evaluated. MDRC has conducted a scan of 82 such programs and will apply lessons from it and other research to a large-scale evaluation of program efficacy that it is currently developing in collaboration with the University System of Georgia. The need for evidence-based approaches that support men of color throughout the educational pipeline is evident, especially at the postsecondary level, where so many male students of color are close to reaching their goals and fulfilling their potential as college graduates