178 research outputs found
On the size of identifying codes in triangle-free graphs
In an undirected graph , a subset such that is a
dominating set of , and each vertex in is dominated by a distinct
subset of vertices from , is called an identifying code of . The concept
of identifying codes was introduced by Karpovsky, Chakrabarty and Levitin in
1998. For a given identifiable graph , let \M(G) be the minimum
cardinality of an identifying code in . In this paper, we show that for any
connected identifiable triangle-free graph on vertices having maximum
degree , \M(G)\le n-\tfrac{n}{\Delta+o(\Delta)}. This bound is
asymptotically tight up to constants due to various classes of graphs including
-ary trees, which are known to have their minimum identifying code
of size . We also provide improved bounds for
restricted subfamilies of triangle-free graphs, and conjecture that there
exists some constant such that the bound \M(G)\le n-\tfrac{n}{\Delta}+c
holds for any nontrivial connected identifiable graph
Triangle-Free Penny Graphs: Degeneracy, Choosability, and Edge Count
We show that triangle-free penny graphs have degeneracy at most two, list
coloring number (choosability) at most three, diameter , and
at most edges.Comment: 10 pages, 2 figures. To appear at the 25th International Symposium on
Graph Drawing and Network Visualization (GD 2017
Decken- und Wandmalerei in Sachsen
Die Broschüre des Landesamtes ist mit der Decken- und Wandmalerei einer besonderen Kunstform gewidmet und stellt Betreuungsaufgaben des Referates Restaurierung vor. Außergewöhnliche Beispiele aus acht Jahrhunderten werden vorgestellt, die teils während Baumaßnahmen entdeckt, gesichert, gerettet, erforscht und restauriert werden konnten. Sie stehen für die Vielfalt in Sachsen, sowohl kunsttechnologisch als auch thematisch. Genauso vielfältig sind die Gebäude, in denen Wand- und Deckenmalereien zu finden sind – und zwar auf dem gesamten Territorium des Freistaats. Die Ausstellung bietet neben Bekanntem auch Überraschungen in eher unscheinbaren Bauten – wer erwartet schon in einem Kindergarten ein Werk Conrad Felixmüllers? Wandmalereien gelten als stets gefährdet, sind sie doch unmittelbar mit dem Mauerwerk verbunden und den Umwelteinflüssen direkt ausgesetzt. Das Spannungsfeld bei der Erhaltung
von Wandmalereien zeigen die ausgewählten Beispiele auf.
Redaktionsschluss: 15.10.202
Doubly connected minimal surfaces and extremal harmonic mappings
The concept of a conformal deformation has two natural extensions:
quasiconformal and harmonic mappings. Both classes do not preserve the
conformal type of the domain, however they cannot change it in an arbitrary
way. Doubly connected domains are where one first observes nontrivial conformal
invariants. Herbert Groetzsch and Johannes C. C. Nitsche addressed this issue
for quasiconformal and harmonic mappings, respectively. Combining these
concepts we obtain sharp estimates for quasiconformal harmonic mappings between
doubly connected domains. We then apply our results to the Cauchy problem for
minimal surfaces, also known as the Bjorling problem. Specifically, we obtain a
sharp estimate of the modulus of a doubly connected minimal surface that
evolves from its inner boundary with a given initial slope.Comment: 35 pages, 2 figures. Minor edits, references adde
A multipurpose experimental facility for advanced X-ray Spectrometry applications
Ponencia presentada en la European Conference on X-Ray Spectrometry (EXRS). 2014Motivation, Ultra High Vacuum Chamber (UHVC) project: To support/enhance the training of scientists/engineers from developing countries in the operation of synchrotron radiation instrumentation; To provide beam time access for R&D projects and hands-on training in SR-XRS based techniques; To promote networking and knowledge sharing; To increase the quality and the competitiveness of the developing countries to apply beam time proposals at SR facilities; To contribute in the further development of XRS techniques in applications with socioeconomicalrelevance (characterization of energy storage/conversion materials, environmental, biological and biomedical applications)Fil: Leani, Juan José. Universidad Nacional de Córdoba. Facultad de Matemática, Astronomía y Física; Argentina.Fil: Leani, Juan José. Nuclear Science and Instrumentation Laboratory, IAEA Laboratories; Austria.Física Atómica, Molecular y Química (física de átomos y moléculas incluyendo colisión, interacción con radiación, resonancia magnética, Moessbauer Efecto.
Über einige Variationsprobleme von GRÖTZSCH bei konformer Abbildung mehrfach zusammenhängender Gebiete
Ein Abbildungssatz für Gebiete, die in eine gegebene Kreisringfläche schlicht eingelagert sind
Wertannahmeprobleme bei quasikonformen Abbildungen mit ortsabhängiger Dilatationsbeschränkung
A Class of Three-Colorable Triangle-Free Graphs
The chromatic number of a triangle-free graph can be arbitrarily large. In this article, we show that if all subdivisions of K2, 3 are also excluded as induced subgraphs, then the chromatic number becomes bounded by 3. We give a structural characterization of this class of graphs, from which we derive an coloring algorithm, where n denotes the number of vertices and m the number of edges of the input graph
- …