A Decidable Confluence Test for Cognitive Models in ACT-R

Computational cognitive modeling investigates human cognition by building detailed computational models for cognitive processes. Adaptive Control of Thought - Rational (ACT-R) is a rule-based cognitive architecture that offers a widely employed framework to build such models. There is a sound and complete embedding of ACT-R in Constraint Handling Rules (CHR). Therefore analysis techniques from CHR can be used to reason about computational properties of ACT-R models. For example, confluence is the property that a program yields the same result for the same input regardless of the rules that are applied. In ACT-R models, there are often cognitive processes that should always yield the same result while others e.g. implement strategies to solve a problem that could yield different results. In this paper, a decidable confluence criterion for ACT-R is presented. It allows to identify ACT-R rules that are not confluent. Thereby, the modeler can check if his model has the desired behavior. The sound and complete translation of ACT-R to CHR from prior work is used to come up with a suitable invariant-based confluence criterion from the CHR literature. Proper invariants for translated ACT-R models are identified and proven to be decidable. The presented method coincides with confluence of the original ACT-R models.Comment: To appear in Stefania Costantini, Enrico Franconi, William Van Woensel, Roman Kontchakov, Fariba Sadri, and Dumitru Roman: "Proceedings of RuleML+RR 2017". Springer LNC

TRUST IN TRANSITION: CROSS COUNTRY AND FIRM EVIDENCE

This paper uses data from a large survey of firms across 26 transition countries to examine the determinants of trust in the transition process. We first introduce a new measure of trust between firms: the level of prepayment demanded by suppliers from their customers in advance of delivery. Using this new measure, we confirm earlier findings that trust is higher where firms have confidence in third party enforcement through the legal system. However, the fairness and honesty of the courts are a more important determinant of interfirm trust than are the courts’ efficiency or ability to enforce decisions. We then examine the role of business networks in building trust and find that networks based around personal ties – family and friends – and business associations actively promote the development of trust, while business networks based on enterprise insiders and government agencies do not. Finally, we find that country-level effects are significantly more important determinants of interfirm trust than are firm-level effects.http://deepblue.lib.umich.edu/bitstream/2027.42/40026/3/wp640.pd

Trust in Transition: Cross-country and Firm Evidence

This paper uses data from a large survey of firms across 26 transition countries to examine the determinants of trust in the transition process. We first introduce a new measure of trust between firms: the level of prepayment demanded by suppliers from their customers in advance of delivery. Using this new measure, we confirm earlier findings that trust is higher where firms have confidence in third party enforcement through the legal system. However, the fairness and honesty of the courts are more important determinants of inter-firm trust than the courts’ efficiency or ability to enforce decisions. We then examine the role of business networks in building trust and find that networks based around personal ties – family and friends – and business associations actively promote the development of trust, while business networks based on enterprise insiders and government agencies do not. Finally, we find that country-level effects are significantly more important determinants of inter-firm trust than firm-level effects.transition, trust, prepayment, courts, business networks

Law and Finance in Transition Economies

This paper offers the first comprehensive analysis of legal change in the protection of shareholder and creditor rights in transition economies and its impact on the propensity of firms to raise external finance. Following La Porta et al. (1998), the paper constructs an expanded set of legal indices to capture a range of potential conflicts between different stakeholders of the firm. It supplements the analysis of the law on the books with an analysis of the effectiveness of legal institutions. Our main finding is that the effectiveness of legal institutions has a much stronger impact on external finance than does the law on the books, despite legal change that has substantially improved shareholder and creditor rights. This finding supports the proposition that legal transplants and extensive legal reforms are not sufficient for the evolution of effective legal and market institutions.shareholder and creditor rights, legal effectiveness, external finance, transition

Making sense of the J-curve: Capital utilisation, output, and total factor productivity in Polish industry 1990 - 1993

The economies of Central and Eastern Europe are undergoing a period of rapid structural change. The general pattern confirms to the J-curve anticipated by several observers at the start of transition. This paper conceptualises the J-curve as the result of a combination of two factors. First, real energy price increases render parts of the capital stock obsolete, due to complementarity between capital and energy in the short run. Second, demand shifts and to a lesser extent efficiency improvements induced by increases in competition cause dramatic changes in total factor productivity. The paper shows for the case of Polish industry that 43 per cent of the capital stock was rendered obsolete over the 1990-1993 period. Total factor productivity fell by 11 per cent in 1990 but had increased to 17 per cent above the 1989 level by 1993. As the capital stock is gradually rebuilt, improvements in efficiency will guarantee an output level higher than before the start of transition.capital ultilisation,efficiency,J-curve,Poland