Solving Parity Games in Scala

Parity games are two-player games, played on directed graphs, whose nodes are labeled with priorities. Along a play, the maximal priority occurring infinitely often determines the winner. In the last two decades, a variety of algorithms and successive optimizations have been proposed. The majority of them have been implemented in PGSolver, written in OCaml, which has been elected by the community as the de facto platform to solve efficiently parity games as well as evaluate their performance in several specific cases. PGSolver includes the Zielonka Recursive Algorithm that has been shown to perform better than the others in randomly generated games. However, even for arenas with a few thousand of nodes (especially over dense graphs), it requires minutes to solve the corresponding game. In this paper, we deeply revisit the implementation of the recursive algorithm introducing several improvements and making use of Scala Programming Language. These choices have been proved to be very successful, gaining up to two orders of magnitude in running time

Time-series cross-sectional environmental performance and disclosure relationship:specific evidence from a less-developed country

This paper relies on ‘vulnerability and exploitability’ framework to submit new insights into legitimacy theory and voluntary disclosure theory using specific empirical evidence from the Nigerian oil and gas industry. The study connects the voluntary and legitimizing disclosure behaviors, regarding carbon emission due to gas flaring, of dominant companies in the Nigerian upstream petroleum sector to the vulnerability and exploitability of Nigeria as a less developed country. The hypothesized relations between gas flaring-related environmental performance and two forms of its disclosure (volume and substance) are estimated and tested using Prais-Winsten regression with Panel Corrected Standard Errors (PCSE). While the paper uses Data Envelopment Analysis (DEA) to measure gas flaring-related carbon performance, the two forms of gas flaring-related disclosures are measured using content analysis. We document significant positive and negative association between gas flaring-related carbon emission performance, on one hand, and the volumetric disclosure and disclosure substance on the other hand. These results imply that while the positive relation confirms the vulnerable nature of Nigeria as a less developed country, the negative relation is linked to the country’s exploitability. It is also empirically established that environmental performance is one of the key factors responsible for the undulating trend in the volume of environmental disclosures by large corporations operating in less-developed countries

A motion system for social and animated robots

This paper presents an innovative motion system that is used to control the motions and animations of a social robot. The social robot Probo is used to study Human-Robot Interactions (HRI), with a special focus on Robot Assisted Therapy (RAT). When used for therapy it is important that a social robot is able to create an "illusion of life" so as to become a believable character that can communicate with humans. The design of the motion system in this paper is based on insights from the animation industry. It combines operator-controlled animations with low-level autonomous reactions such as attention and emotional state. The motion system has a Combination Engine, which combines motion commands that are triggered by a human operator with motions that originate from different units of the cognitive control architecture of the robot. This results in an interactive robot that seems alive and has a certain degree of "likeability". The Godspeed Questionnaire Series is used to evaluate the animacy and likeability of the robot in China, Romania and Belgium