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We investigate methods and tools for analyzing translations between programming languages with respect to observational semantics. The behavior of programs is observed in terms of may- and mustconvergence in arbitrary contexts, and adequacy of translations, i.e., the reflection of program equivalence, is taken to be the fundamental correctness condition. For compositional translations we propose a notion of convergence equivalence as a means for proving adequacy. This technique avoids explicit reasoning about contexts, and is able to deal with the subtle role of typing in implementations of language extensions.
We investigate methods and tools for analysing translations between programming languages with respect to observational semantics. The behaviour of programs is observed in terms of may- and mustconvergence in arbitrary contexts, and adequacy of translations, i.e., the reflection of program equivalence, is taken to be the fundamental correctness condition. For compositional translations we propose a notion of convergence equivalence as a means for proving adequacy. This technique avoids explicit reasoning about contexts, and is able to deal with the subtle role of typing in implementations of language extensions.
We investigate methods and tools for analysing translations between programming languages with respect to observational semantics. The behaviour of programs is observed in terms of may- and mustconvergence in arbitrary contexts, and adequacy of translations, i.e., the reflection of program equivalence, is taken to be the fundamental correctness condition. For compositional translations we propose a notion of convergence equivalence as a means for proving adequacy. This technique avoids explicit reasoning about contexts, and is able to deal with the subtle role of typing in implementations of language extensions.
This paper proves several generic variants of context lemmas and thus contributes to improving the tools for observational semantics of deterministic and non-deterministic higher-order calculi that use a small-step reduction semantics. The generic (sharing) context lemmas are provided for may- as well as two variants of must-convergence, which hold in a broad class of extended process- and extended lambda calculi, if the calculi satisfy certain natural conditions. As a guide-line, the proofs of the context lemmas are valid in call-by-need calculi, in callby-value calculi if substitution is restricted to variable-by-variable and in process calculi like variants of the π-calculus. For calculi employing beta-reduction using a call-by-name or call-by-value strategy or similar reduction rules, some iu-variants of ciu-theorems are obtained from our context lemmas. Our results reestablish several context lemmas already proved in the literature, and also provide some new context lemmas as well as some new variants of the ciu-theorem. To make the results widely applicable, we use a higher-order abstract syntax that allows untyped calculi as well as certain simple typing schemes. The approach may lead to a unifying view of higher-order calculi, reduction, and observational equality.
We present a higher-order call-by-need lambda calculus enriched with constructors, case-expressions, recursive letrec-expressions, a seq-operator for sequential evaluation and a non-deterministic operator amb that is locally bottom-avoiding. We use a small-step operational semantics in form of a single-step rewriting system that defines a (nondeterministic) normal order reduction. This strategy can be made fair by adding resources for bookkeeping. As equational theory we use contextual equivalence, i.e. terms are equal if plugged into any program context their termination behaviour is the same, where we use a combination of may- as well as must-convergence, which is appropriate for non-deterministic computations. We show that we can drop the fairness condition for equational reasoning, since the valid equations w.r.t. normal order reduction are the same as for fair normal order reduction. We evolve different proof tools for proving correctness of program transformations, in particular, a context lemma for may- as well as mustconvergence is proved, which restricts the number of contexts that need to be examined for proving contextual equivalence. In combination with so-called complete sets of commuting and forking diagrams we show that all the deterministic reduction rules and also some additional transformations preserve contextual equivalence.We also prove a standardisation theorem for fair normal order reduction. The structure of the ordering <=c a is also analysed: Ω is not a least element, and <=c already implies contextual equivalence w.r.t. may-convergence.
This paper discusses the effect of capital regulation on the risk taking behavior of commercial banks. We first theoretically show that capital regulation works differently in different market structures of banking sectors. In lowly concentrated markets, capital regulation is effective in mitigating risk taking behavior because banks' franchise values are low and banks have incentives to pursue risky strategies in order to increase their franchise values. If franchise values are high, on the other hand, the effect of capital regulation on bank risk taking is ambiguous as banks lack those incentives. We then test the model predictions on a cross-country sample including 421 commercial banks from 61 countries. We find that capital regulation is effective in mitigating risk taking only in markets with a low degree of concentration. The results remain robust after accounting for financial sector development, legal system effciency, and for other country and bank-specific characteristics. Keywords: Banks, market structure, risk shifting, franchise value, capital regulation
CONTENTS Preamble 1. Concept and Drivers of Globalization 1.0 A Brief Historical Perspective 1.1 Concept of Globalization 1.2 Economic Globalization 1.3 Drivers of Economic Globalization 2. Globalization and Markets 2.1 The Free Market System 2.2 Markets and the Solution of Economic Problems 2.3 African Markets and “Getting the Prices Right”. 2.4 Implications of the Imperfect Market System 2.5 Government’s Inevitable Role 2.6 The International Environment/Markets 3. Globalization and Trade Liberalisation 3.1 The Experience of the Developing Countries 3.2 Nigeria’s Experience with Trade Liberalisation 4. Global Economic Integration and Sub-Saharan Africa 4.1 Global Economic Integration 4.2 Africa’s Integration with the World Economy 4.3 The Benefits of Economic Globalization and Sub-Saharan Africa 4.4 Why has Africa Lagged? 5. Nigeria and the Global Economy 5.1 Openness of the Economy and Integration with the World Economy 5.2 Globalization and Nigeria’s Trade 5.3 Globalization and Foreign Capital Flows to Nigeria 5.4 Foreign Capital Flows and Debt Accumulation 5.5 Globalization, Growth and Development 6. Appropriate Policy Responses and Lessons 7. Concluding Remarks 8. Appreciation 9. Annex 10. References