Search results for " Graphs"
showing 10 items of 62 documents
Decremental 2- and 3-connectivity on planar graphs
1996
We study the problem of maintaining the 2-edge-, 2-vertex-, and 3-edge-connected components of a dynamic planar graph subject to edge deletions. The 2-edge-connected components can be maintained in a total ofO(n logn) time under any sequence of at mostO(n) deletions. This givesO(logn) amortized time per deletion. The 2-vertex- and 3-edge-connected components can be maintained in a total ofO(n log2n) time. This givesO(log2n) amortized time per deletion. The space required by all our data structures isO(n). All our time bounds improve previous bounds.
Le paysage, entre esthétique & écologie : modélisation rétrospective à partir de changements d'occupation du sol
2016
Landscape is both a backdrop to the lives of human populations and a medium for the life cycle of animal species. Landscape changes induced by land-use and land-cover dynamics affect both these dimensions, the one aesthetic, and the other ecological. Because these rationales areusually studied within different disciplines, little research has been done into how the two clashor combine as and when landscape structures change. This work seeks therefore to model the spatial co-evolution of the aesthetic and ecological functions of landscape retrospectively usingspatial metrics based on land-cover data. It focuses on changes in the urban fringes of two French cities (Paris and Besançon) over th…
Fillets:Cues for connections in Focus+Context views of graph-like diagrams
2003
We apply fillets-smoothing of sharp angles at the joints-between the connections and nodes of graph-like diagrams. In situations where the graph layout is constrained, e.g. Focus+Context views or views where the coordinates of the nodes are informative, fillets can clarify the relationships considerably without altering the layout. A visual search experiment supports our hypothesis that with fillets it is considerably easier to perceive node-connection structures. We discuss algorithms with different tradeoffs for flexibility and performance for rendering these connections in a single pass using OpenGL.
Conceptual graph operations for formal visual reasoning in the medical domain
2014
International audience; Objective - Conceptual graphs (CGs) are used to represent clinical guidelines because they support visual reasoning with a logical background, making them a potentially valuable representation for guidelines.Materials and methods - Conceptual graph formalism has an essential and basic component: a formal vocabulary that drives all of the other mechanisms, notably specialization and projection. The graph's theoretical operations, such as projection, rules, derivation, constraints, probabilities and uncertainty, support diagrammatic reasoning.Results - A conceptual graph's graphical user interface includes a multilingual vocabulary management, some query and decision-m…
Annealed Invariance Principle for Random Walks on Random Graphs Generated by Point Processes in R-d
2016
International audience; We consider simple random walks on random graphs embedded in R-d and generated by point processes such as Delaunay triangulations, Gabriel graphs and the creek-crossing graphs. Under suitable assumptions on the point process, we show an annealed invariance principle for these random walks. These results hold for a large variety of point processes including Poisson point processes, Matern cluster and Matern hardcore processes which have respectively clustering and repulsiveness properties. The proof relies on the use the process of the environment seen from the particle. It allows to reconstruct the original process as an additive functional of a Markovian process und…
Analyzing online search patterns of music festival tourists
2020
Music festivals, as cultural events that induce tourism flows, intermediate both the cultural and travel experience. The present study analyzes online search behavior of potential attenders to a music festival. We hypothesize that the search process reveals latent patterns of behavior of cultural tourists planning to attend music festivals. To this end, information from Google Trends on queries related to three popular music festivals is used to build a network of search topics. Based on it, alternative exponential random graph model specifications are estimated. Findings support the general result of mediated information flows: music festivals induce planning and traveling queries. Howeve…
UNIQUELY HAMILTONIAN GRAPHS. A TALK IN THREE PARTS
2018
Professor of UWA Gordon Royle gives a talk in Singapour devoted to UH3 graphs, graphs with unique Hamiltonian cycle with vertex degree at least three
Using 2-colorings in the theory of uniquely Hamiltonian graphs
2019
We use the concept of 2-coloring in analyzing UH3 graphs and building exact specifications of functions to find new UH3 graphs by Hamiltonian cycle edge extractions
Modeling and Mitigating Errors in Belief Propagation for Distributed Detection
2021
We study the behavior of the belief-propagation (BP) algorithm affected by erroneous data exchange in a wireless sensor network (WSN). The WSN conducts a distributed multidimensional hypothesis test over binary random variables. The joint statistical behavior of the sensor observations is modeled by a Markov random field whose parameters are used to build the BP messages exchanged between the sensing nodes. Through linearization of the BP message-update rule, we analyze the behavior of the resulting erroneous decision variables and derive closed-form relationships that describe the impact of stochastic errors on the performance of the BP algorithm. We then develop a decentralized distribute…
Two examples related to conical energies
2022
In a recent article we introduced and studied conical energies. We used them to prove three results: a characterization of rectifiable measures, a characterization of sets with big pieces of Lipschitz graphs, and a sufficient condition for boundedness of nice singular integral operators. In this note we give two examples related to sharpness of these results. One of them is due to Joyce and M\"{o}rters, the other is new and could be of independent interest as an example of a relatively ugly set containing big pieces of Lipschitz graphs.