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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
This paper discusses the implications of transnational media production and diasporic networks for the cultural politics of migrant minorities. How are fields of cultural politics transformed if Hirschmann’s famous options ‘exit’ and ‘voice’ are no longer constituting mutually exclusive responses to dissent within a nation-state, but modes of action that can combine and build upon each other in the context of migration and diasporic media activism? Two case studies are discussed in more detail, relating to Alevi amateur television production in Germany and to a Kurdish satellite television station that reaches out to a diaspora across Europe and the Middle East. Keywords: migrant media, transnationalism, Alevis, Kurds, Turkey, Germany
Hong Kong’s Linked Exchange Rate System (LERS) has been in operation for twenty-five years during which time many other fixed exchange rate systems have succumbed to shocks and/or speculative attacks. This fact alone suggests that the LERS is a robust system which enjoys a large measure of credibility in financial markets. This paper intends to investigate whether this is indeed the case, and whether it has been the case throughout its 25-year history. In particular we will use the tools of modern finance to extract information from financial asset prices about market expectations that are related to the credibility of the LERS. The main focus is on how market participants ‘judged’ the various changes made to the LERS, such as the ‘seven technical measures’ introduced in September 1998 and the ‘three refinements’ made in May 2005. These changes have been characterizes as making the system less discretionary over time, and we hypothesize that they have also made it more credible as revealed in the prices of exchange rate related asset prices. We also investigate the relationship between interest rates and exchange rates in the current system in light of modern models of target-zone exchange rate systems. We will examine whether the intramarginal intervention in November 2007 changed the dynamic properties of the exchange rate as suggested by such models.
Ensuring financial stability : financial structure and the impact of monetary policy on asset prices
(2008)
This paper studies the responses of residential property and equity prices, inflation and economic activity to monetary policy shocks in 17 countries, using data spanning 1986-2006. We estimate VARs for individual economies and panel VARs in which we distinguish between groups of countries on the basis of the characteristics of their financial systems. The results suggest that using monetary policy to offset asset price movements in order to guard against financial instability may have large effects on economic activity. Furthermore, while financial structure influences the impact of policy on asset prices, its importance appears limited. Keywords: asset prices, monetary policy, panel VAR. JEL Number: C23, E52
Recently, the Bank of Japan outlined a “two perspectives” approach to the conduct of monetary policy that focuses on risks to price stability over different time horizons. Interpreting this as pertaining to different frequency bands, we use band spectrum regression to study the determination of inflation in Japan. We find that inflation is related to money growth and real output growth at low frequencies and the output gap at higher frequencies. Moreover, this relationship reflects Granger causality from money growth and the output gap to inflation in the relevant frequency bands. Keywords: spectral regression, frequency domain, Phillips curve, quantity theory. JEL Numbers: C22, E3, E5
We study the effect of randomness in the adversarial queueing model. All proofs of instability for deterministic queueing strategies exploit a finespun strategy of insertions by an adversary. If the local queueing decisions in the network are subject to randomness, it is far from obvious, that an adversary can still trick the network into instability. We show that uniform queueing is unstable even against an oblivious adversary. Consequently, randomizing the queueing decisions made to operate a network is not in itself a suitable fix for poor network performances due to packet pileups.
Purim and parodies
(2008)