Nominal C-Unification

Nominal unification is an extension of first-order unification that takes into account the \alpha-equivalence relation generated by binding operators, following the nominal approach. We propose a sound and complete procedure for nominal unification with commutative operators, or nominal C-unification for short, which has been formalised in Coq. The procedure transforms nominal C-unification problems into simpler (finite families) of fixpoint problems, whose solutions can be generated by algebraic techniques on combinatorics of permutations.Comment: Pre-proceedings paper presented at the 27th International Symposium on Logic-Based Program Synthesis and Transformation (LOPSTR 2017), Namur, Belgium, 10-12 October 2017 (arXiv:1708.07854

Nominal Logic Programming

Nominal logic is an extension of first-order logic which provides a simple foundation for formalizing and reasoning about abstract syntax modulo consistent renaming of bound names (that is, alpha-equivalence). This article investigates logic programming based on nominal logic. We describe some typical nominal logic programs, and develop the model-theoretic, proof-theoretic, and operational semantics of such programs. Besides being of interest for ensuring the correct behavior of implementations, these results provide a rigorous foundation for techniques for analysis and reasoning about nominal logic programs, as we illustrate via examples.Comment: 46 pages; 19 page appendix; 13 figures. Revised journal submission as of July 23, 200

Nominal Unification from a Higher-Order Perspective

Nominal Logic is a version of first-order logic with equality, name-binding, renaming via name-swapping and freshness of names. Contrarily to higher-order logic, bindable names, called atoms, and instantiable variables are considered as distinct entities. Moreover, atoms are capturable by instantiations, breaking a fundamental principle of lambda-calculus. Despite these differences, nominal unification can be seen from a higher-order perspective. From this view, we show that nominal unification can be reduced to a particular fragment of higher-order unification problems: Higher-Order Pattern Unification. This reduction proves that nominal unification can be decided in quadratic deterministic time, using the linear algorithm for Higher-Order Pattern Unification. We also prove that the translation preserves most generality of unifiers

Learning morphological phenomena of Modern Greek an exploratory approach

This paper presents a computational model for the description of concatenative morphological phenomena of modern Greek (such as inflection, derivation and compounding) to allow learners, trainers and developers to explore linguistic processes through their own constructions in an interactive open‐ended multimedia environment. The proposed model introduces a new language metaphor, the ‘puzzle‐metaphor’ (similar to the existing ‘turtle‐metaphor’ for concepts from mathematics and physics), based on a visualized unification‐like mechanism for pattern matching. The computational implementation of the model can be used for creating environments for learning through design and learning by teaching

Monetary Union and Central Bank Independence

We study the consequences of forming a monetary union among a group of countries where the central banks lack independence and are pressured frequently to accommodate government objectives. This is a common situation in the developing countries. As it is common in the literature, we show that forming a monetary union yields net benefits if output shocks are similar across the member countries and if one or more countries in the union can serve as anchors. Our framework highlights an additional gain from monetary union. We show that the opportunistic objectives of one country's policymakers are kept in check at the union level by other members with disparate objectives. Hence, monetary union can improve the monetary policy for its members if the pressures on the individual central banks are dissimilar. We calibrate the model to evaluate the proposed monetary union in the East African Community. Working Paper 06-5

Regional Currency Arrangements: Insights from Europe

This paper focuses on the requirements and features of a successful monetary union on the basis of the optimum currency area theory, the “logical roadmap” for integration as proposed by Balassa as well as the economic and institutional framework of the European Economic and Monetary Union (EMU). The analysis suggests that monetary union is contingent upon high economic integration and strong political commitment. However, political union is not an ex-ante requirement. Outside factors such as systemic shocks and globalization seem to speed up the pooling of sovereignty in the economic domain. A firm commitment to stability-oriented monetary and fiscal policies is a precondition for gaining credibility and trust within and outside a monetary union. Last, but not least, convergence criteria, fiscal rules and strong institutions are necessary to help ensure and monitor the participants’ compliance. However, the European experience is not a blueprint for regional integration that can be directly and entirely applied to other regions.Economic and Monetary Integration; International Monetary Arrangements and Institutions; Monetary Policy and Central Banking; Macroeconomic Policy Formation

Multiple-sensor integration for efficient reverse engineering of geometry

This paper describes a multi-sensor measuring system for reverse engineering applications. A sphere-plate artefact is developed for data unification of the hybrid system. With the coordinate data acquired using the optical system, intelligent feature recognition and segmentation algorithms can be applied to extract the global surface information of the object. The coordinate measuring machine (CMM) is used to re-measure the geometric features with a small amount of sampling points and the obtained information can be subsequently used to compensate the point data patches which are measured by optical system. Then the optimized point data can be exploited for accurate reverse engineering of CAD model. The limitations of each measurement system are compensated by the other. Experimental results validate the accuracy and effectiveness of this data optimization approach

The dual corporate income tax in China: the impact of unification

For many years, foreign funded companies in China enjoyed a relatively low tax rate and a series of preferential policies which were aimed at encouraging foreign direct investment in China. By adopting a new law in 2007, however, the National People's Congress proclaimed the end of the dual corporate-income-tax system. From 2008, the preferential tax treatment of foreign capital will be phased out. As a result, the income tax rate for domestic and foreign funded companies will be unified at the rate of 25%. This paper explores the impact of the dual corporate income tax system on both domestic and foreign funded enterprises and discusses the possible effects of the unification.dual corporate income tax, China, unification, foreign funded enterprises