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See detailZ_2^n-Supergeometry I: Manifolds and Morphisms
Covolo, Tiffany UL; Grabowski, Janusz; Poncin, Norbert UL

E-print/Working paper (2014)

Detailed reference viewed: 269 (73 UL)
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See detailD’méisproochegt Gehir
Engel de Abreu, Pascale UL

E-print/Working paper (2014)

Den „kognitive Virdeel“ vun der Méisproochegkeet besteet doranner, datt méisproocheg Kanner a bestëmmte kognitiven Aufgaben, déi déi sougenannten „Exekutivfunktioune“ moossen, besser si wéi Kanner, déi ... [more ▼]

Den „kognitive Virdeel“ vun der Méisproochegkeet besteet doranner, datt méisproocheg Kanner a bestëmmte kognitiven Aufgaben, déi déi sougenannten „Exekutivfunktioune“ moossen, besser si wéi Kanner, déi nëmmen eng Sprooch schwätzen. [less ▲]

Detailed reference viewed: 141 (9 UL)
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See detailIs there a Bubble in the Art Market?
Kräussl, Roman UL; Lehnert, Thorsten UL; Martelin, Nicolas

E-print/Working paper (2014)

Detailed reference viewed: 1201 (82 UL)
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See detailRisk and Expected Returns of Private Equity Investments: Evidence Based on Market Prices
Kräussl, Roman UL; Jegadeesh, Jegadeesh; Pollet, Joshua M.

E-print/Working paper (2014)

Detailed reference viewed: 109 (0 UL)
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See detailNews Media Sentiment and Investor Behavior
Kräussl, Roman UL; Mirgorodskaya, Elizaveta

E-print/Working paper (2014)

Detailed reference viewed: 16 (0 UL)
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See detailA very good triple of operads
Riviere, Salim UL

E-print/Working paper (2013)

Detailed reference viewed: 53 (0 UL)
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See detailLeitfaden wissenschaftliches Arbeiten - Wie schreibe ich eine Hausarbeit und wie präsentiere ich sie?
Heinz, Andreas UL; Reuter, Julia; Zillien, Nicole

E-print/Working paper (2013)

Detailed reference viewed: 527 (24 UL)
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See detailProduct Unbundling in the Travel Industry: The Economics of Airline Bag Fees
Brueckner, Jan K.; Lee, Darin N.; Picard, Pierre M UL et al

E-print/Working paper (2013)

This paper provides theory and evidence on airline bag fees, offering insights into a real-world case of product unbundling. The theory predicts that an airline’s fares should fall when it introduces a ... [more ▼]

This paper provides theory and evidence on airline bag fees, offering insights into a real-world case of product unbundling. The theory predicts that an airline’s fares should fall when it introduces a bag fee, but that the full trip price (the bag fee plus the new fare) could either rise or fall. The empirical evidence presented in the paper provides strong confirmation of this prediction. The data also suggest that the average fare falls by less than the bag fee itself, so that the full price of a trip rises for passengers who choose to check bags. [less ▲]

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See detailTimeliness in Selected Structural Credit Risk Models
Jin, Xisong UL; Lehnert, Thorsten UL; Nadal de Simone, Francisco

E-print/Working paper (2013)

We empirically investigate and evaluate various approaches to structurally assess credit risk changes using a panel of selected European banking groups. The objective is to evaluate the models according ... [more ▼]

We empirically investigate and evaluate various approaches to structurally assess credit risk changes using a panel of selected European banking groups. The objective is to evaluate the models according to one metric, i.e., their ability to correctly and timely identify changes in credit risk indicators useful for macroprudential policy. We consider not only the standard approaches in the literature, but also include models that allow the asset volatility to be stochastic and models that allow for short- and long-term components of default risk. Surprisingly, we find that the GARCH structural credit risk model, despite its more sophisticated modeling approach, typically underperforms more basic models. Importantly for macro-prudential policy, combining the Merton model with the GARCH-MIDAS model performs best and reflects important market events earlier than the other approaches. [less ▲]

Detailed reference viewed: 77 (1 UL)
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See detailDoes it Pay to Invest in Art? A Selection-corrected Returns Perspective
Kräussl, Roman UL; Korteweg, Arthur; Verwijmeren, Patrick

E-print/Working paper (2013)

Detailed reference viewed: 102 (11 UL)
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See detailThe Effect of Anticipated and Experienced Regret and Pride on Investors’ Future Selling Decisions*
Kräussl, Roman UL; Lee, Carmen; Paas, Leo

E-print/Working paper (2013)

Detailed reference viewed: 64 (1 UL)
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See detailDas mehrsprachige Gehirn
Engel de Abreu, Pascale UL

E-print/Working paper (2013)

Der „kognitive Vorteil“ der Mehrsprachigkeit besteht darin, dass mehrsprachige Kinder in bestimmten kognitiven Aufgaben, welche die sogenannten „exekutiven Funktionen“ messen, besser sind als Kinder, die ... [more ▼]

Der „kognitive Vorteil“ der Mehrsprachigkeit besteht darin, dass mehrsprachige Kinder in bestimmten kognitiven Aufgaben, welche die sogenannten „exekutiven Funktionen“ messen, besser sind als Kinder, die nur eine Sprache sprechen. [less ▲]

Detailed reference viewed: 225 (9 UL)
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See detailMacroeconomic Foundations of Financial Predictability
Mehra, Rajnish UL; Donaldson, J.B.

E-print/Working paper (2013)

Detailed reference viewed: 139 (9 UL)
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See detailUpside down with the strong partial clones
Schölzel, Karsten UL

E-print/Working paper (2013)

Detailed reference viewed: 33 (5 UL)
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See detailCobham's theorem for abstract numeration systems
Charlier, Emilie; Leroy, Julien UL; Rigo, Michel

E-print/Working paper (2013)

Detailed reference viewed: 22 (0 UL)
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See detailAsymmetric contests with risky rents
Guigou, Jean-Daniel UL

E-print/Working paper (2013)

Detailed reference viewed: 54 (4 UL)
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See detailRights offerings, trading and regulation : a global perspective
Vermaelen, Theo UL; Massa, Massimo; Moqi, Xu

E-print/Working paper (2013)

Detailed reference viewed: 59 (0 UL)
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See detailBuybacks around the world
Vermaelen, Theo UL; Peyer, Urs; Manconi, Alberto

E-print/Working paper (2013)

Detailed reference viewed: 61 (1 UL)
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See detailDeclining bargaining power of workers and the rise of early retirement in Europe
Batyra, Anna; de la Croix, David; Pierrard, Olivier et al

E-print/Working paper (2013)

We offer an alternative explanation for the decline in labor force participation of senior workers. Typically, tax and transfer explanations have been proposed. On the contrary, a model with imperfectly ... [more ▼]

We offer an alternative explanation for the decline in labor force participation of senior workers. Typically, tax and transfer explanations have been proposed. On the contrary, a model with imperfectly competitive labor market allows to consider as well the effects of a drop in bargaining power, which would not be possible in a purely neoclassical framework. We find that a decline in the bargaining power of workers, which has taken place in the last four decades, has largely contributed to the rise in inactivity in Europe. However, we need a combination of these two explanations, along with population aging and a fall in the matching efficiency, in order to correctly reproduce the joint evolutions of other labor market variables such as the employment and unemployment rates. [less ▲]

Detailed reference viewed: 945 (4 UL)
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See detailSkewness Risk Premium: Theory and Empirical Evidence
Lehnert, Thorsten UL; Wolff, Christian UL; Lin, Yuehao

E-print/Working paper (2013)

Detailed reference viewed: 162 (4 UL)
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See detailStein’s Overeaction Puzzle: Option Anomaly or Perfectly Rational Behavior
Lehnert, Thorsten UL; Martelin, Nicolas UL; Lin, Yuehao

E-print/Working paper (2013)

Detailed reference viewed: 75 (5 UL)
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See detailThe Impact of Policy Interventions on Stock Liquidity
Lehnert, Thorsten UL; Busch, Thomas

E-print/Working paper (2013)

Detailed reference viewed: 25 (3 UL)
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See detailEstimation Risk in Option Pricing
Lehnert, Thorsten UL; Bams, Dennis; Blanchard, Gildas

E-print/Working paper (2013)

Detailed reference viewed: 44 (3 UL)
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See detailWashington Meets Wall Street: A Closer Examination of the Presidential Cylce Puzzle
Kräussl, Roman UL; Lucas, André; Rijsbergen, David R. et al

E-print/Working paper (2013)

Detailed reference viewed: 34 (2 UL)
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See detailHas Europe Been Catching Up? An Industry Level Analysis of Venture Capital Success over 1985-2009*
Kräussl, Roman UL; Krause, Stefan

E-print/Working paper (2013)

Detailed reference viewed: 60 (2 UL)
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See detailThe index of an Eisenstein ideal of multiplicity one
Yoo, Hwajong UL

E-print/Working paper (2013)

Mazur’s fundamental work on Eisenstein ideals for prime level has a variety of arith- metic applications. In this article, we generalize his work to arbitrary square-free level. We compute the index of an ... [more ▼]

Mazur’s fundamental work on Eisenstein ideals for prime level has a variety of arith- metic applications. In this article, we generalize his work to arbitrary square-free level. We compute the index of an Eisenstein ideal and the dimension of the m-torsion of the modular Jacobian vari- ety, where m is an Eisenstein maximal ideal. In many cases, the dimension of the m-torsion is 2, in other words, multiplicity one theorem holds. [less ▲]

Detailed reference viewed: 167 (3 UL)
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See detailFrom tax evasion to tax planning
Bourgain, Arnaud UL; Pieretti, Patrice UL; Zanaj, Skerdilajda UL

E-print/Working paper (2013)

This paper analyzes within a simple model how a removal of bank secrecy can impact tax revenues and banks'profitability, assuming that offshore centers are able to offer sophisticated but legal, tax ... [more ▼]

This paper analyzes within a simple model how a removal of bank secrecy can impact tax revenues and banks'profitability, assuming that offshore centers are able to offer sophisticated but legal, tax planning. Two alternative regimes are considered. A first, in which there is strict bank secrecy and a second, where there is international information exchange for tax purposes. In particular, we show that sharing tax information with onshore countries can be a dominant strategy for an OFC if there is enough scope for providing tax planning. Moreover, a partial reduction of tax liabilities can already prompt OFCs to voluntarily exchange relevant tax information. We also discuss the conditions under which the possible removal of bank secrecy may reduce or increase the onshore country's tax revenue. [less ▲]

Detailed reference viewed: 278 (109 UL)
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See detailModeling default correlation in a US retail loan portfolio
Pisa, Magdalena UL; Wolff, Christian UL; Bams, Dennis

E-print/Working paper (2012)

Detailed reference viewed: 67 (1 UL)
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See detailVertically Splitting a Firm:Promotion and Demotion in a Team Production Experiment
Neugebauer, Tibor UL; LACOMBA, JUAN A.; FATAS, ENRIQUE et al

E-print/Working paper (2012)

Detailed reference viewed: 19 (1 UL)
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See detailSentiment Trades and Option Prices
Lehnert, Thorsten UL; Frijns, Bart; Zwinkels, Remco

E-print/Working paper (2012)

Detailed reference viewed: 12 (0 UL)
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See detailLectures on Supergeometry
Covolo, Tiffany UL; Poncin, Norbert UL

E-print/Working paper (2012)

Detailed reference viewed: 428 (129 UL)
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See detailFiber bundles and connections
Poncin, Norbert UL

E-print/Working paper (2012)

Detailed reference viewed: 151 (24 UL)
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See detailThe Governance of Perpetual Financial Intermediaries
Van Bommel, Jos UL; Penalva, José

E-print/Working paper (2012)

Detailed reference viewed: 82 (4 UL)
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See detailLimited Liability, Moral Hazard and Risk Taking – A Safety Net Game
Neugebauer, Tibor UL; Füllbrunn, Sascha

E-print/Working paper (2012)

Detailed reference viewed: 23 (1 UL)
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See detailNoise Trading and the Cross-Section of Index Option Prices
Irek, Fabian UL; Frijns, Bart; Lehnert, Thorsten UL et al

E-print/Working paper (2012)

Detailed reference viewed: 27 (1 UL)
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See detailExcludability and Contribution: A Laboratory Study in Team Production
Neugebauer, Tibor UL; Fatás; Croson

E-print/Working paper (2012)

Detailed reference viewed: 75 (1 UL)
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See detailDoes the GARCH Structural Credit Risk Model Make a Difference?
Jin, Xisong UL; Lehnert, Thorsten UL

E-print/Working paper (2011)

In this study, we empirically investigate and evaluate various approaches to structurally assess credit risk using a panel of European banking groups. We consider not only the standard approaches in the ... [more ▼]

In this study, we empirically investigate and evaluate various approaches to structurally assess credit risk using a panel of European banking groups. We consider not only the standard approaches in the literature, but also include models that allow the asset volatility to be stochastic and models that allow for short- and long-term components of default risk. Models are evaluated by comparing their ability to correctly and timely identify changes in risk indicators. Surprisingly, we find that the GARCH structural credit risk model, despite its more sophisticated modeling approach, typically underperforms more basic models. Importantly for macro-prudential policy, the combined Merton/GARCH-MIDAS model performs best and reflects important market events earlier than the other approaches. [less ▲]

Detailed reference viewed: 124 (3 UL)
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See detailThe Relative Informational Efficiency of Stocks, Options and Credit Default Swaps
Bekkour, Lamia UL; Lehnert, Thorsten UL; Chiara Amadori, Maria

E-print/Working paper (2011)

Detailed reference viewed: 64 (1 UL)
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See detailTransparency and Ending Times of Call Auctions: A Comparison of Euronext and Xetra
Van Bommel, Jos UL; Hoffmann, Peter

E-print/Working paper (2011)

Detailed reference viewed: 43 (1 UL)
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See detailStrategic Delegation and Collusion: Do Incentive Schemes Matter?
Guigou, Jean-Daniel UL; de Lamirande, Patrick; Lovat, Bruno

E-print/Working paper (2011)

Detailed reference viewed: 23 (0 UL)
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See detailFinancial Intermediation in an Overlapping Generations Model with Transaction Costs
Van Bommel, Jos UL; Hasman, Augusto; Samartin, Margarita

E-print/Working paper (2011)

Detailed reference viewed: 95 (2 UL)
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See detailPublic Good and Private Good Valuation for Waiting, Time Reduction: A Laboratory Study
Neugebauer, Tibor UL; Traub, Stefan

E-print/Working paper (2011)

Detailed reference viewed: 57 (1 UL)
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See detailCultural Values, CEO Risk Aversion and Corporate Takeovers
Lehnert, Thorsten UL; Frijns, Bart; Gilbert, Aaron et al

E-print/Working paper (2011)

Detailed reference viewed: 72 (2 UL)
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See detailCorporate Governance and Financial Development: A Study of the French Case
Guigou, Jean-Daniel UL; Boughanmi, Afef; Defffains, Bruno et al

E-print/Working paper (2011)

Detailed reference viewed: 77 (2 UL)
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See detailLectures on Algebraic Operads
Hilger, Patrick; Poncin, Norbert UL

E-print/Working paper (2011)

Detailed reference viewed: 148 (18 UL)
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See detailThe Relative Informational Efficiency of Stocks, Options and Credit Default Swaps
Bekkour, Lamia UL; Lehnert, Thorsten UL; Amadori, Maria Chiara

E-print/Working paper (2011)

Detailed reference viewed: 65 (2 UL)
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See detailGeorges-Louis Leclerc de Buffon’s ‘Essays on Moral Arithmetic
Neugebauer, Tibor UL; Hey, John D.; Pasca, Carmen M

E-print/Working paper (2010)

Detailed reference viewed: 118 (1 UL)
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See detailWho makes the pie bigger? An experimental study on co-opetition
Neugebauer, Tibor UL; Lacomba, Juan A.; Lagos, Francisco

E-print/Working paper (2010)

Detailed reference viewed: 83 (1 UL)
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See detailContingent Capital: The Case for COERCs
Wolff, Christian UL; Vermaelen, Theo UL; Pennacchi, George

E-print/Working paper (2010)

Detailed reference viewed: 19 (0 UL)
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See detailModeling structural changes in the volatility process
Lehnert, Thorsten UL; Frijns, Bart; C.J. Zwinkels, Remco

E-print/Working paper (2010)

Detailed reference viewed: 55 (1 UL)
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See detailLimited Liability, Moral Hazard and Risk Taking - A Safety Net Game Experiment
Neugebauer, Tibor UL; Füllbrunn, Sascha

E-print/Working paper (2010)

Detailed reference viewed: 59 (4 UL)
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See detailThéorie des représentations du groupe symétrique
Hilger, Patrick; Poncin, Norbert UL

E-print/Working paper (2009)

Detailed reference viewed: 61 (4 UL)
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See detailA Cumulative Prospect Theory Approach to Option Pricing
Lehnert, Thorsten UL; Wolff, Christian UL; Versluis, Cokki

E-print/Working paper (2009)

Detailed reference viewed: 138 (0 UL)
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See detailDispersion of Beliefs in the Foreign Exchange Market
Wolff, Christian UL; Jongen, Ron; Willem F.C., Verschoor et al

E-print/Working paper (2009)

Detailed reference viewed: 11 (0 UL)
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See detailBehavioral Heterogeneity in the Option Market
Lehnert, Thorsten UL; Frijns, Bart; Zwinkels, Remco

E-print/Working paper (2009)

Detailed reference viewed: 59 (0 UL)
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See detailTime-Variation in Term Permia: International Survey-Based Evidence
Wolff, Christian UL; Jongen, Ron; F.C. Verschoor, Willem

E-print/Working paper (2009)

Detailed reference viewed: 22 (0 UL)
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See detailLaw, corporate governance and financial system: Econometric analysis of French case
Guigou, Jean-Daniel UL; Boughanmi, Afef; Blazy, Régis UL et al

E-print/Working paper (2008)

Detailed reference viewed: 35 (0 UL)
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See detailLoss Functions in Option Valuation: A Framework for Selection
Lehnert, Thorsten UL; Wolff, Christian UL; Bams, Dennis

E-print/Working paper (2008)

Detailed reference viewed: 72 (0 UL)
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See detailAn Experimental Analysis of Optimal Renewable Resource Management:The Fishery
Neugebauer, Tibor UL; Hey, John D; Sadrieh, Abdolkarim

E-print/Working paper (2008)

Detailed reference viewed: 59 (1 UL)
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See detailAre Capital Controls in the Foreign Exchange Market Effective?
Wolff, Christian UL; Straetmans, Stefan T.M.; Versteeg, Roald J.

E-print/Working paper (2008)

Detailed reference viewed: 56 (0 UL)
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See detailOn maximal independent sets in circulant digraphs
Bisdorff, Raymond UL

E-print/Working paper (2007)

In this research note we introduce St-Nicolas graphs, i.e. circulant digraphs showing exactly n maximal independent sets, isomorph under the digraph’s automorphisms group. This class of digraphs represent ... [more ▼]

In this research note we introduce St-Nicolas graphs, i.e. circulant digraphs showing exactly n maximal independent sets, isomorph under the digraph’s automorphisms group. This class of digraphs represent a generalisation of Andrásfai graphs with interesting links to finite group theory. [less ▲]

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See detailRelative Performance Evaluation, Risk Aversion and Entry
Guigou, Jean-Daniel UL; Lovat, Bruno; Piaser, Gwenaël UL

E-print/Working paper (2007)

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See detailFinancial versus Social Efficiency of Corporate Bankruptcy Law: the French Dilemma ?
Guigou, Jean-Daniel UL; BLAZY, Régis UL; CHOPARD, Bertrand et al

E-print/Working paper (2007)

Detailed reference viewed: 68 (0 UL)
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See detailEvaluation des performances relatives, risque et entrée
Guigou, Jean-Daniel UL; Lovat, B.

E-print/Working paper (2006)

Detailed reference viewed: 24 (0 UL)
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See detailImpact de l’attrait des places bancaires sur les taux d’intérêt créditeurs : Un modèle de formation des taux créditeurs estimé sur données en panel de banques européennes
Bourgain, Arnaud UL; Pieretti, Patrice UL; Rouabah, Abdelaziz

E-print/Working paper (2001)

This article evaluates the impact of banking centers' attractiveness on deposit interest rates. Using balance-sheet data from a set of 135 banks, the authors test an intermediation model of deposit rate ... [more ▼]

This article evaluates the impact of banking centers' attractiveness on deposit interest rates. Using balance-sheet data from a set of 135 banks, the authors test an intermediation model of deposit rate determination. In particular, the investigation shows a significant impact of « confidentiality » on deposit rates, thus confirming the importance of qualitative variables favouring local differentiation and clustering of banking activities. [less ▲]

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See detailEffets de complémentarité externes et incidence sur la productivité : le cas de l'industrie manufacturière luxembourgeoise
Bourgain, Arnaud UL; Pieretti, Patrice UL

E-print/Working paper (2001)

This article seeks to measure knowledge spillovers between nearby industries. This represents one of types of externality identified in the studies of industry location. A spillover indicator is suggested ... [more ▼]

This article seeks to measure knowledge spillovers between nearby industries. This represents one of types of externality identified in the studies of industry location. A spillover indicator is suggested which can explain increasing returns at the aggregate level. It is shown that this indicator is positively related to industry diversity. As applied to data from Luxembourg’s manufacturing industry, this indicator suggests that labor productivity is increasing in industry diversity. [less ▲]

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See detailOn linear decompositions of L-valued simple graphs
Bisdorff, Raymond UL

E-print/Working paper (1996)

In this report we will present a linear decomposition of a given L- valued binary relation into a set of sub-relations of kernel-dimension one. We will apply this theoretical result to the design of a ... [more ▼]

In this report we will present a linear decomposition of a given L- valued binary relation into a set of sub-relations of kernel-dimension one. We will apply this theoretical result to the design of a faster algorithm for computing L-valued kernels on general L-valued simple graphs. [less ▲]

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See detailKummer theory for number fields via entanglement groups
Perucca, Antonella UL; Sgobba, Pietro UL; Tronto, Sebastiano UL

E-print/Working paper (n.d.)

Let $K$ be a number field, and let $G$ be a finitely generated and torsion-free subgroup of $K^\times$. We are interested in computing the degree of the cyclotomic-Kummer extension $K(\sqrt[n]{G})$ over ... [more ▼]

Let $K$ be a number field, and let $G$ be a finitely generated and torsion-free subgroup of $K^\times$. We are interested in computing the degree of the cyclotomic-Kummer extension $K(\sqrt[n]{G})$ over $K$, where $\sqrt[n]{G}$ consists of all $n$-th roots of the elements of $G$. We develop the theory of entanglements introduced by Lenstra, and apply it to compute the above degrees. [less ▲]

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See detailWeakening the tight coupling between geometry and simulation in isogeometric analysis: from sub- and super- geometric analysis to Geometry Independent Field approximaTion (GIFT)
Atroshchenko, Elena; Xu, Gang; Tomar, Satyendra UL et al

E-print/Working paper (n.d.)

This paper presents an approach to generalize the concept of isogeometric analysis (IGA) by allowing different spaces for parameterization of the computational domain and for approximation of the solution ... [more ▼]

This paper presents an approach to generalize the concept of isogeometric analysis (IGA) by allowing different spaces for parameterization of the computational domain and for approximation of the solution field. The method inherits the main advantage of isogeometric analysis, i.e. preserves the original, exact CAD geometry (for example, given by NURBS), but allows pairing it with an approximation space which is more suitable/flexible for analysis, for example, T-splines, LR-splines, (truncated) hierarchical B-splines, and PHT-splines. This generalization offers the advantage of adaptive local refinement without the need to re-parameterize the domain, and therefore without weakening the link with the CAD model. We demonstrate the use of the method with different choices of the geometry and field splines, and show that, despite the failure of the standard patch test, the optimum convergence rate is achieved for non-nested spaces. [less ▲]

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See detailReductions of points on algebraic groups II
Bruin, Peter; Perucca, Antonella UL

E-print/Working paper (n.d.)

Detailed reference viewed: 8 (1 UL)
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See detailKummer extensions of number fields (the case of rank 2) II
Perucca, Antonella UL

E-print/Working paper (n.d.)

Detailed reference viewed: 14 (1 UL)
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See detailThe problem of detecting linear dependence
Perucca, Antonella UL

E-print/Working paper (n.d.)

Detailed reference viewed: 58 (1 UL)
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See detailThe degree of Kummer extensions of number fields
Perucca, Antonella UL; Sgobba, Pietro UL; Tronto, Sebastiano UL

E-print/Working paper (n.d.)

Detailed reference viewed: 65 (4 UL)
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See detailExplicit Kummer Theory for the rational numbers
Perucca, Antonella UL; Sgobba, Pietro UL; Tronto, Sebastiano UL

E-print/Working paper (n.d.)

Detailed reference viewed: 138 (21 UL)
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See detailKummer theory for one-dimensional tori
Perucca, Antonella UL; Navas Orozco, Jesús

E-print/Working paper (n.d.)

Detailed reference viewed: 37 (5 UL)
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See detailExplicit Kummer theory for quadratic fields
Hörmann, Fritz; Perucca, Antonella UL; Sgobba, Pietro UL et al

E-print/Working paper (n.d.)

Let K be a number field, and let \alpha \in K be an algebraic number which is neither 0 nor a root of unity. The ratio between n and the Kummer degree [K(\zeta_m,\sqrt[n]{\alpha}):K(\zeta_m)], where n ... [more ▼]

Let K be a number field, and let \alpha \in K be an algebraic number which is neither 0 nor a root of unity. The ratio between n and the Kummer degree [K(\zeta_m,\sqrt[n]{\alpha}):K(\zeta_m)], where n divides m, is known to be bounded independently of n and m. For some families of quadratic number fields we describe an explicit algorithm that provides formulas for all those Kummer degrees. In particular, for the given fields we are able to give explicit expressions for the Kummer extensions contained in a cyclotomic extension. [less ▲]

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See detailA new one point quadrature rule over arbitrary star convex polygon/polyhedron
Natarajan, Sundararajan; Francis, Amrita; Atroshchenko, Elena et al

E-print/Working paper (n.d.)

The Linear Smoothing (LS) scheme \cite{francisa.ortiz-bernardin2017} ameliorates linear and quadratic approximations over convex polytopes by employing a three-point integration scheme. In this work, we ... [more ▼]

The Linear Smoothing (LS) scheme \cite{francisa.ortiz-bernardin2017} ameliorates linear and quadratic approximations over convex polytopes by employing a three-point integration scheme. In this work, we propose a linearly consistent one point integration scheme which possesses the properties of the LS scheme with three integration points but requires one third of the integration computational time. The essence of the proposed technique is to approximate the strain by the smoothed nodal derivatives that are determined by the discrete form of the divergence theorem. This is done by the Taylor's expansion of the weak form which facilitates the evaluation of the smoothed nodal derivatives acting as stabilization terms. The smoothed nodal derivatives are evaluated only at the centroid of each integration cell. These integration cells are the simplex subcells (triangle/tetrahedron in two and three dimensions) obtained by subdividing the polytope. The salient feature of the proposed technique is that it requires only $n$ integrations for an $n-$ sided polytope as opposed to $3n$ in~\cite{francisa.ortiz-bernardin2017} and $13n$ integration points in the conventional approach. The convergence properties, the accuracy, and the efficacy of the LS with one point integration scheme are discussed by solving few benchmark problems in elastostatics. [less ▲]

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See detailLinear smoothed polygonal and polyhedral finite elements
Francis, Amrita; Ortiz-Bernardin, Alejandro; Bordas, Stéphane UL et al

E-print/Working paper (n.d.)

It was observed in [1, 2] that the strain smoothing technique over higher order elements and arbitrary polytopes yields less accurate solutions than other techniques such as the conventional polygonal ... [more ▼]

It was observed in [1, 2] that the strain smoothing technique over higher order elements and arbitrary polytopes yields less accurate solutions than other techniques such as the conventional polygonal finite element method. In this work, we propose a linear strain smoothing scheme that improves the accuracy of linear and quadratic approximations over convex polytopes. The main idea is to subdivide the polytope into simplicial subcells and use a linear smoothing function in each subcell to compute the strain. This new strain is then used in the computation of the stiffness matrix. The convergence properties and accuracy of the proposed scheme are discussed by solving few benchmark problems. Numerical results show that the proposed linear strain smoothing scheme makes the approximation based on polytopes to deliver improved accuracy and pass the patch test to machine precision. [less ▲]

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See detailLinear smoothed extended finite element method
Murugesan; Natarajan, Sundararajan; Gadyam, Palani et al

E-print/Working paper (n.d.)

The extended finite element method (XFEM) was introduced in 1999 to treat problems involving discontinuities with no or minimal remeshing through appropriate enrichment functions. This enables elements to ... [more ▼]

The extended finite element method (XFEM) was introduced in 1999 to treat problems involving discontinuities with no or minimal remeshing through appropriate enrichment functions. This enables elements to be split by a discontinuity, strong or weak and hence requires the integration of discontinuous functions or functions with discontinuous derivatives over elementary volumes. Moreover, in the case of open surfaces and singularities, special, usually non-polynomial functions must also be integrated.A variety of approaches have been proposed to facilitate these special types of numerical integration, which have been shown to have a large impact on the accuracy and convergence of the numerical solution. The smoothed extended finite element method (SmXFEM) [1], for example, makes numerical integration elegant and simple by transforming volume integrals into surface integrals. However, it was reported in [1, 2] that the strain smoothing is inaccurate when non-polynomial functions are in the basis. This is due to the constant smoothing function used over the smoothing domains which destroys the effect of the singularity. In this paper, we investigate the benefits of a recently developed Linear smoothing procedure [3] which provides better approximation to higher order polynomial fields in the basis. Some benchmark problems in the context of linear elastic fracture mechanics (LEFM) are solved to compare the standard XFEM, the constant-smoothed XFEM (Sm-XFEM) and the linear-smoothed XFEM (LSm-XFEM). We observe that the convergence rates of all three methods are the same. The stress intensity factors (SIFs) computed through the proposed LSm-XFEM are however more accurate than that obtained through Sm-XFEM. To conclude, compared to the conventional XFEM, the same order of accuracy is achieved at a relatively low computational effort. [less ▲]

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