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Université de Fribourg

On the minimum and maximum selective graph coloring problems in some graph classes

Ries, Bernard

In: Discrete Applied Mathematics, 2016, vol. 204, p. 77-89

Given a graph together with a partition of its vertex set, the minimum selective coloring problem consists of selecting one vertex per partition set such that the chromatic number of the subgraph induced by the selected vertices is minimum. The contribution of this paper is twofold. First, we investigate the complexity status of the minimum selective coloring problem in some specific graph...

Université de Fribourg

NPO zwischen Ignoranz, Konkurrenz und Kooperation

Gmuer, Markus

In: Verbands-Management, 2019, vol. 45, no. 1, p. 6-15

Verbände und andere NPO haben mehrere Optionen im Umgang mit anderen Organisationen, die ihnen in der Ressourcenbeschaffung oder der Leistungserbringung in die Quere kommen: Sie können sich erstens für Konkurrenz entscheiden und dazu eine Wettbewerbsposition suchen, die sie in den Augen ihrer Stakeholder besonders attraktiv erscheinen lässt. Sie können zweitens die Option der ...

Université de Fribourg

Bilder der Organisation und ihre Bedeutung für NPO

Gmuer, Markus

In: Verbands-Management, 2019, vol. 45, no. 1, p. 44-53

In diesem Beitrag werden in Anlehnung an den Ansatz «Images of Organization» von Gareth Morgan zehn verschiedene Blickwinkel für die Analyse von Organisationsproblemen und mögliche Lösungsansätze eingeführt: Demnach lassen sich Organisationen sowohl als Maschinen als auch als Organismen oder Gehirne, als Kulturen, psychische Gefängnisse und Prozessepisoden, als Marktplätze oder ...

Université de Fribourg

Fusionen : Alternative für existenzbedrohte Stiftungen?

Schunk, Martin

In: Verbands-Management, 2019, vol. 45, no. 1, p. 30-34

Mergers and Acquisitions, Fusionen und Zusammenschlüsse: Begriffe die uns regelmässig bei der Durchsicht von Wirtschaftsmagazinen begegnen. Auch für gemeinnützige Stiftungen können Fusionen oder Zusammenschlüsse von wachsender Bedeutung sein. Da besonders kleine Stiftungen von der Niedrigzinsphase betroffen sind, können sie ihre Attraktivität für Sponsoren und Geldgeber durch eine...

Université de Fribourg

Do Anti-Corruption Educational Campaigns Reach Students? : Evidence from Russia and Ukraine

Denisova-Schmidt, Elena ; Huber, Martin ; Leontyeva, Elvira

In: Educational studies. Moscow, 2016, no. 1, p. 61-83

The authors investigate the effect of anti-corruption educational materials — an informational folder with materials designed by Transparency International — on the willingness of students to participate in an anti-corruption campaign and their general judgment about corruption in two cities in Russia and Ukraine by conducting experiments. During a survey of 350 students in Khabarovsk,...

Public access from 20-feb-2021
Université de Fribourg

Classifying k-edge colouring for H-free graphs

Galby, Esther ; T. Lima, Paloma ; Paulusma, Daniël ; Ries, Bernard

In: Information procesing letters, 2019, vol. 146, p. 39-43

A graph is H-free if it does not contain an induced subgraph isomorphic to H. For every integer k and every graph H, we determine the computational complexity of k-Edge Colouring for H-free graphs.

Public access from 22-giu-2020
Université de Fribourg

Contraction and deletion blockers for perfect graphs and H-free graphs

Y. Diner, Öznur ; Paulusma, Daniël ; Picouleau, Christophe ; Ries, Bernard

In: Theoretical computer science, 2018, vol. 746, p. 49-72

We study the following problem: for given integers d, k and graph G, can we reduce some fixed graph parameter π of G by at least d via at most k graph operations from some fixed set S? As parameters we take the chromatic number χ, clique number ω and independence number α, and as operations we choose edge contraction ec and vertex deletion vd. We determine the complexity of this problem...

Université de Fribourg

Local Average Treatment Effects with or Without Defiers

Dahl, Christian M. ; Huber, Martin ; Mellace, Giovanni

In: Discussion papers on business and economics, 2017, vol. 2, p. 1-69

In heterogeneous treatment effect models with endogeneity, identification of the LATE typically relies on the availability of an exogenous instrument monotonically related to treatment participation. We demonstrate that a strictly weaker local monotonicity condition identifies the LATEs on compliers and on defiers. We propose simple estimators that are potentially more efficient than 2SLS,...

Université de Fribourg

Testing for covariate balance using quantile regression and resampling methods

Huber, Martin

In: Journal of applied statistics, 2011, vol. 38, no. 12, p. 2881-2899

Consistencyofpropensityscorematchingestimatorshingesonthepropensityscore’sabilityt obalancethe distributions of covariates in the pools of treated and non-treated units. Conventional balance tests merely check for differences in covariates’means, but cannot account for differences in higher moments. For this ...

Université de Fribourg

Treatment evaluation in the presence of sample selection

Huber, Martin

In: Econometric reviews, 2014, vol. 33, no. 8, p. 869-905

Sample selection and attrition are inherent in a range of treatment evaluation problems such as the estimation of the returns to schooling or training. Conventional estimators tackling selection bias typically rely on restrictive functional form assumptions that are unlikely to hold in reality. This paper shows identification of average and quantile treatment effects in the presence of the...