Academic literature on the topic 'Graphes de groupes'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the lists of relevant articles, books, theses, conference reports, and other scholarly sources on the topic 'Graphes de groupes.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Journal articles on the topic "Graphes de groupes"
1
Sergiescu, Vlad. "Graphes planaires et présentations des groupes de tresses." Mathematische Zeitschrift 214, no. 1 (September 1993): 477–90. http://dx.doi.org/10.1007/bf02572418.
Full text
2
Zara, François. "Une Caractérisation des Graphes Associés aux Groupes de Fischer." European Journal of Combinatorics 7, no. 2 (April 1986): 187–90. http://dx.doi.org/10.1016/s0195-6698(86)80045-2.
Full text
3
Imbert, Michel. "Calculs de Présentations de Groupes Fuchsiens via les Graphes Rubanés." Expositiones Mathematicae 19, no. 3 (2001): 213–27. http://dx.doi.org/10.1016/s0723-0869(01)80002-5.
Full text
4
Kassouk, Zeineb, Jean-Claude Thouret, and Akhmad Solikhin. "L'apport de l'imagerie à haute résolution spatiale à la cartographie du risque de crue torentielle." Revue Française de Photogrammétrie et de Télédétection, no. 209 (November 18, 2014): 109–16. http://dx.doi.org/10.52638/rfpt.2015.132.
Full textAbstract:
Dans ce travail nous étudions le flanc sud du volcan Merapi (Indonésie) dévasté par la grande éruption de 2010 (IEV 4). Nous poursuivons trois objectifs : (1) Identifier les dépôts pyroclastiques et de lahars grâce à la classification «orientée-objet» appliquée à trois images GeoEye-1 (1,64 m ; 15/10/2010 et 29/07/2011) et Pléiades (0,5 m ; 29/10/2012). Ces dépôts pyroclastiques comprennent les écoulements denses canalisés, ceux qui ont débordé des vallées et les déferlantes diluées à l'amont du bassin et sur les marges des vallées. (2) Suivre l'évolution temporelle de ces dépôts grâce aux indices spectraux calculés pour chaque image. Nous avons appliqué la classification orientée-objet aux indices spectraux, NDWI, NDVI et NDRSI (Indice Normalisée du Sol Rouge). Les résultats ont permis d'identifier 15 classes de dépôts pyroclastiques, de lahars et les zones affectés dans la vallée de Gendol-Opak ( Ì´80 km²), qui représentent 75% de classes obtenues par photo-interprétation de l'image et appuyées par des observations de terrain. Les indices NDWI et NDVI ont mis en évidence les zones affectées par les déferlantes (NDWI <0,2 et 0,1<NDVI<0,3) et la végétation indemne (0,2<NDWI<0,4; NDVI<0,16). Les indices NDWI et NDRSI ont permis de distinguer les dépôts canalisés (NDRSI<-0.3 et 0,1<NDWI<0,2) des zones couvertes par les lahars (NDRSI>0,3 et NDWI<0,1). Un NDRSI proche de 0 a été attribué à des dépôts «rougeâtres», probablement riches en scories oxydées. L'analyse bivariée des trois indices spectraux NDWI, NDVI et NDRSI a permis de suivre l'évolution temporelle post-éruption. Le graphe NDVI/NDWI en 2010 montre deux groupes : l'un attribué aux écoulements denses canalisés (NDVI et NDWI proches de 0), l'autre séparant les zones de forêt et rizières intactes de celles affectées par les déferlantes. Le graphe NDWI/NDRSI indique deux groupes différents, attribués aux dépôts riches en scories (NDRSI<0,1) et aux écoulements denses qui ont débordé (NDWI<0,12 et NDRSI<-0.3). En 2011 et 2012, les trois graphes NDVI/NDWI, NDWI/NDRSI et NDVI/NDRSI montrent deux groupes bien séparés (forêt et rizières) contrastant avec les dépôts de lahars et des écoulements denses qui avaient débordé sur les marges des vallées.
5
A. Jund, Asaad, and Haval M. Mohammed Salih. "Result Involution Graphs of Finite Groups." Journal of Zankoy Sulaimani - Part A 23, no. 1 (June 20, 2021): 113–18. http://dx.doi.org/10.17656/jzs.10846.
Full text
6
Wang, Xuan Lun, and Wei Jiu Huang. "Fabrication and Characterization of Graphene/Polyimide Nanocomposites." Advanced Materials Research 785-786 (September 2013): 138–44. http://dx.doi.org/10.4028/www.scientific.net/amr.785-786.138.
Full textAbstract:
Graphene/polyimide nanocomposites with different weight loadings were prepared by a solution compounding technique. Graphene was synthesized from graphite oxide that was fabricated by the Hummers method. X-ray diffraction (XRD), ultraviolet visible (UV-vis) spectra and simultaneous thermal analysis were used for the microstructure analysis of the graphenes. Graphenes with single layer structure were synthesized successfully and had good solubility in water or other polar solvents due to a few functional groups on the graphene carbons. Graphenes have good thermal stability. Mechanical and tribological properties were studied for the graphene/polyimide composites. The composites have excellent strength and toughness with very small graphene loading level and the addition of graphene decreased the friction coefficient and wear rate of the composites.
7
Ma, Wen Shi, Jun Wen Zhou, and Xiao Dan Lin. "X-Ray Photoelectron Spectroscopy Study on Reduction of Graphene Oxide with Hydrazine Hydrate." Advanced Materials Research 287-290 (July 2011): 539–43. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.539.
Full textAbstract:
Graphene oxide was prepared through Hummers' method，then different reduced graphenes were prepared via reduction of graphene oxide with hydrazine hydrate for 1h、12h and 24h. X-ray photoelectron spectroscopy (XPS) was used for the characterization of graphene oxide and the reduced graphenes. The variation of the contents of carbon in carbon and oxygen functional groups and chemical compositions of graphene oxides were investigated through analysis the content of different carbon atoms in different reduced graphenes. The results showed that the reduction reaction was very fast in the first 1 h, the content of total oxygen bonded carbon atoms decreased from 83.6% to 22.1%, and then after the reduction rate became very slow. After 12h, the content of total oxygen bonded carbon atom is 19.56%, only 2.54% lower than that of 1h’s. At the same time, C-N was introduced in the graphene oxides; this increased the stereo-hindrance for hydrazine hydrate attacking the C-Oxygen groups, thus reduced the reduction rate. After reduction for 24h, there still exists 16.4% oxygen bonded carbon atoms and the total conversion ratio of graphene approaches 70%.
8
Cowan, David, and Norman R. Reilly. "Characterizations of Schützenberger graphs in terms of their automorphism groups and fundamental groups." Glasgow Mathematical Journal 35, no. 3 (September 1993): 275–91. http://dx.doi.org/10.1017/s0017089500009861.
Full textAbstract:
AbstractThe importance of the fundamental group of a graph in group theory has been well known for many years. The recent work of Meakin, Margolis and Stephen has shown how effective graph theoretic techniques can be in the study of word problems in inverse semigroups. Our goal here is to characterize those deterministic inverse word graphs that are Schutzenberger graphs and consider how deterministic inverse word graphs and Schutzenberger graphs can be constructed from subgroups of free groups.
9
Strankowski, Michał, Damian Włodarczyk, Łukasz Piszczyk, and Justyna Strankowska. "Polyurethane Nanocomposites Containing Reduced Graphene Oxide, FTIR, Raman, and XRD Studies." Journal of Spectroscopy 2016 (2016): 1–6. http://dx.doi.org/10.1155/2016/7520741.
Full textAbstract:
Recently, graphene and other graphene-based materials have become an essential part of composite science and technology. Their unique properties are not only restricted to graphene but also shared with derivative compounds like graphene oxide, reduced graphene oxide, functionalized graphene, and so forth. One of the most structurally important materials, graphene oxide (GO), is prepared by the oxidation of graphite. Though removal of the oxide groups can create vacancies and structural defects, reduced graphene oxide (rGO) is used in composites as effective filler similar to GO. Authors developed a new polyurethane nanocomposite using a derivative of grapheme, thermally reduced graphene oxide (rGO), to modify the matrix of polyurethane elastomers, by rGO.
10
Brang, David, Stanley Kanai, Vilayanur S. Ramachandran, and Seana Coulson. "Contextual Priming in Grapheme–Color Synesthetes and Yoked Controls: 400 msec in the Life of a Synesthete." Journal of Cognitive Neuroscience 23, no. 7 (July 2011): 1681–96. http://dx.doi.org/10.1162/jocn.2010.21486.
Full textAbstract:
Grapheme–color synesthesia is a heritable trait where graphemes (“2”) elicit the concurrent perception of specific colors (red). Researchers have questioned whether synesthetic experiences are meaningful or simply arbitrary associations and whether these associations are perceptual or conceptual. To address these fundamental questions, ERPs were recorded as 12 synesthetes read statements such as “The Coca-Cola logo is white and 2,” in which the final grapheme induced a color that was either contextually congruous (red) or incongruous (“…white and 7,” for a synesthetes who experienced 7 as green). Grapheme congruity was found to modulate the amplitude of the N1, P2, N300, and N400 components in synesthetes, suggesting that synesthesia impacts perceptual as well as conceptual aspects of processing. To evaluate whether observed ERP effects required the experience of colored graphemes versus knowledge of grapheme–color pairings, we ran three separate groups of controls on a similar task. Controls trained to a synesthete's associations elicited N400 modulation, indicating that knowledge of grapheme–color mappings was sufficient to modulate this component. Controls trained to synesthetic associations and given explicit visualization instructions elicited both N300 and N400 modulations. Lastly, untrained controls who viewed physically colored graphemes (“2” printed in red) elicited N1 and N400 modulations. The N1 grapheme congruity effect began earlier in synesthetes than colored grapheme controls but had similar scalp topography. Data suggest that, in synesthetes, achromatic graphemes engage similar visual processing networks as colored graphemes in nonsynesthetes and are in keeping with models of synesthesia that posit early feed-forward connections between form and color processing areas in extrastriate cortex. The P2 modulation was unique to the synesthetes and may reflect neural activity that underlies the conscious experience of the synesthetic induction.
Dissertations / Theses on the topic "Graphes de groupes"
1
Moioli, Christophe. "Graphes de groupes et groupes co-hopfiens." Phd thesis, Université Paul Sabatier - Toulouse III, 2013. http://tel.archives-ouvertes.fr/tel-00961301.
Full textAbstract:
Un groupe est dit co-hopfien si tout endomorphisme injectif de ce groupe est un automorphisme. En utilisant la théorie de Bass-Serre, nous montrons sous quelles conditions certains graphes de groupes, ayant leurs groupes d'arêtes finis, ont des groupes fondamentaux co-hopfiens. Nous montrons aussi, en utilisant le scindement JSJ de Bowditch, que tout groupe hyperbolique à un bout est co-hopfien. Ce résultat généralise un résultat de Sela au cas avec torsion. Nous terminons avec un algorithme général décidant, étant donné un groupe hyperbolique, si ce groupe est co-hopfien ou non.
2
Tanasescu, Mihaela-Cerasela. "Graphes, Partitions et Classes : G-graphs et leurs applications." Thesis, Antilles-Guyane, 2014. http://www.theses.fr/2014AGUY0787/document.
Full textAbstract:
Les graphes définis à partir de structures algébriques possèdent d’excellentes propriétés de symétries particulièrement intéressantes. L’exemple le plus flagrant est la notion de graphe de Cayley qui s’est révélée très riche non seulement du point de vue théorique mais aussi pratique par ses applications à de nombreux domaines incluant l’architecture des réseaux ou les machines parallèles. Néanmoins, la régularité des graphes de Cayley se révèle parfois être une limite étant donné qu’ils sont toujours sommet-transitifs et donc en particulier non pertinents pour générer des réseaux semiréguliers.Cette observation a motivé, en 2005, la définition d’une nouvelle classe de graphes définis à partir d’un groupe, appelés G-graphes. Ils possèdent aussi de nombreuses propriétés de régularité mais de manière moins restrictive.Cette thèse propose un nouveau regard sur cette classe de graphes par une approche plutôt orientée recherche opérationnelle alors que la grande majorité des études précédentes est dominée par des approches essentiellement algébriques. Nous-nous sommes alors intéressés à plusieurs questions :— La caractérisation des G-graphes : nous proposons des améliorations par rapport aux précédents résultats.— Identifier des classes de graphes comme des G-graphes grâce à des isomorphismes ou en utilisant le théorème de caractérisation.— Etudier la structure et les propriétés de ces graphes, en particulier pour de possibles applications aux réseaux : colorations semi-régulières, symétries et robustesse.— Une approche algorithmique pour la reconnaissance de cette classe avec notamment un premier exemple de cas polynomial lorsque le groupe est abélienInteractions between graph theory and group theory have already led to interesting results for both domains. Graphs defined from algebraic groups have highly symmetrical structure giving birth to interesting properties. The most famous example is Cayley graphs, which revealed to be particularly interesting both from a theoretical and a practical point of view due to their applications in several domains including network architecture or parallel machines. Nevertheless, the regularity of Cayley graphs is also a limit as they are always vertex-transitive and therefore not relevant to generate semi-regular networks. This observation motivated the definition, in 2005, of a new family of graphs defined from a group, called G-graphs. They also have many regular properties but are less restrictive. These graphs are in particular semi-regular k-partite, with a chromatic number k directly given in the group representation and they can be either transitive or not.This thesis proposes a new insight into this class of graphs using an approach based on operational research while most of previous studies have been so far dominated by algebraic approaches. Then, the thesis addresses different kind of questions:— Characterizing G-graphs: we propose improvements of previous results.— Identifying some classes of graphs as G-graphs through isomorphism or using the characterization theorem.— Studying the structure and properties of these graphs, in particular for possible applications to networks: semi-regular coloring, symmetries and robustness.— Algorithmic approach for recognizing this class with a first example of polynomial case when the group is abelian
3
Scapellato, Raffaele. "Contributions à la théorie des groupes et à la théorie des graphes : groupes finis matroidaux et graphes géodétiques généralisés." Toulouse 3, 1990. http://www.theses.fr/1990TOU30213.
Full textAbstract:
Cette these est constituee par trois parties: (i), (ii) et (iii): i) on generalise le theoreme des bases de burnside a la classe des groupes matroidaux. On precise la structure des groupes matroidaux a sous-groupe de frattini trivial. On montre que les p-groupes dedoubles s'obtiennent canoniquement par extension d'un p-groupe possedant un systeme generateur x et un automorphisme qui inverse tout element de x; ii) on etudie l'influence des ordres des elements d'un groupe fini sur sa structure. On calcule le diametre du graphe de commutativite de plusieurs groupes. On decrit completement les groupes nilpotents et les groupes infinis possedant une fonction de steiner; iii) on classifie les graphes geodetiques de diametre 2. On etudie les graphes f-geodetiques (ou le nombre des geodesiques reliant deux sommets est une fonction donnee, dependant de la distance entre eux). On montre qu'un graphe f-geodetique biparti est regulier si et seulement si il est distance-regulier
4
De, Loynes Basile. "Graphes et marches aléatoires." Phd thesis, Université Rennes 1, 2012. http://tel.archives-ouvertes.fr/tel-00726483.
Full textAbstract:
L'étude des marches aléatoires fait apparaître des connexions entre leurs propriétés algébriques, géométriques ou encore combinatoires et leurs propriétés stochastiques. Si les marches aléatoires sur les groupes - ou sur des espaces homogènes - fournissent beaucoup d'exemples, il serait appréciable d'obtenir de tels résultats de rigidité sur des structures algébriques plus faibles telles celles de semi-groupoide ou de groupoide. Dans cette thèse il est considéré un exemple de semi-groupoide et un exemple de groupoide, tous les deux sont définis a partir de sous-graphes contraints du graphe de Cayley d'un groupe - le premier graphe est dirige alors que le second ne l'est pas. Pour ce premier exemple, on précise un résultat de Campanino et Petritis (ils ont montre que la marche aléatoire simple était transiente pour cet exemple de graphe dirigé) en déterminant la frontière de Martin associée à cette marche et établissant sa trivialité Dans le second exemple apparaissant dans ce manuscrit, on considère des pavages quasi-périodiques de l'espace euclidien obtenus à l'aide de la méthode de coupe et projection. Nous considérons la marche aléatoire simple le long des arêtes des polytopes constituant le pavage, et nous répondons a la question du type de celle-ci, c'est-à-dire nous déterminons si elle est récurrente ou transiente. Nous montrons ce résultat en établissant des inégalités isopérimétriques Cette stratégie permet d'obtenir des estimées de la vitesse de décroissance du noyau de la chaleur, ce que n'aurait pas permis l'utilisation d'un critère de type Nash-Williams.
5
Vonseel, Audrey. "Hyperbolicité et bouts des graphes de Schreier." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAD025/document.
Full textAbstract:
Cette thèse est consacrée à l'étude de la topologie à l'infini d'espaces généralisant les graphes de Schreier. Plus précisément, on considère le quotient X/H d'un espace métrique géodésique propre hyperbolique X par un groupe quasi-convexe-cocompact H d'isométries de X. On montre que ce quotient est un espace hyperbolique. Le résultat principal de cette thèse indique que le nombre de bouts de l'espace quotient X/H est déterminé par les classes d'équivalence sur une sphère de rayon explicitement calculable. Dans le cadre de la théorie des groupes, on montre que l'on peut construire explicitement des groupes et des sous-groupes pour lesquels il n'existe pas d'algorithme permettant de déterminer le nombre de bouts relatifs. Si le sous-groupe est quasi-convexe, on donne un algorithme permettant de calculer le nombre de bouts relatifsThis thesis is devoted to the study of the topology at infinity of spaces generalizing Schreier graphs. More precisely, we consider the quotient X/H of a geodesic proper hyperbolic metric space X by a quasiconvex-cocompact group H of isometries of X. We show that this quotient is a hyperbolic space. The main result of the thesis indicates that the number of ends of the quotient space X/H is determined by equivalence classes on a sphere of computable radius. In the context of group theory, we show that one can construct explicitly groups and subgroups for which there are no algorithm to determine the number of relative ends. If the subgroup is quasiconvex, we give an algorithm to compute the number of relative ends
6
Beeker, Benjamin. "Problèmes géométriques et algorithmiques dans des graphes de groupes." Caen, 2011. http://www.theses.fr/2011CAEN2043.
Full textAbstract:
Cette thèse en théorie géométrique des groupes présente plusieurs résultats géométriques et algorithmiques sur les groupes de Baumslag-Solitar généralisés à rang variable (vGBS). Les groupes vGBS sont les groupes admettant une décomposition en graphe de groupes à groupes de sommet et d'arête abéliens libres de type fini. Nous donnons tout d'abord une description détaillé des décompositions JSJ abéliennes des groupes vGBS. Nous décrivons ensuite les décompositions JSJ de compatibilité de ces groupes. Nous démontrons que dans la classe des groupes vGBS, le JSJ abélien classique est algorithmiquement constructible tandis que le JSJ abélien de compatibilité ne l'est pas. Dans un dernier chapitre nous étudions le problème de conjugaison multiple. Nous montrons que, bien que le problème général soit indécidable, il devient résoluble sous certaines restrictionsThis thesis in geometric group theory gives geometric and algorithmic results on the class of generalized Baumslag-Solitar groups of variable rank (vGBS groups). A vGBS group is one that admits a splitting in a graph of groups where all vertex and edge groups are finitely generated free abelian. We first give a description of the abelian JSJ splittings of vGBS groups. We then describe their abelian compatibility JSJ splittings. We show that, in the class of vGBS groups, the “usual” JSJ splitting is algorithmically constructible, while the compatibility JSJ splitting is not. Finaly we study the multiple conjugacy problem. We show that, although the general problem is undecidable, it is solvable under certain restrictions
7
Gauyacq, Ginette. "Routages uniformes dans les graphes sommet-transitifs." Bordeaux 1, 1995. http://www.theses.fr/1995BOR10574.
Full textAbstract:
En 1989, m. C. Heydemann, j. C. Meyer et d. Sotteau ont conjecture que, dans tout graphe sommet-transitif, il existe un routage de plus courtes chaines sommet-uniformes et ont demontre que leur conjecture etait vraie dans le cas particulier des graphes de cayley. Dans cette these on definit de nouvelles classes de graphes sommet-transitifs dans lesquels il existe un routage de plus courtes chaines sommet-uniforme: les graphes quasi-cayley, les graphes a k-orbites regulieres. On etudie les proprietes de ces nouvelles classes, en particulier les proprietes algebriques de leurs groupes d'automorphismes. Un corollaire de cette etude est que la conjecture est vraie pour les graphes sommet-transitifs de diametre 2. On donne des exemples de familles de graphes quasi-cayley qui ne sont pas des graphes de cayley, des exemples de familles de graphes a k-orbites regulieres qui ne sont pas des graphes quasi-cayley. A cette occasion, on etudie la couverture par des cycles sommet-disjoints de l'ensemble des sommets de certains odd-graphs et de certains graphes de johnson ce qui permet d'introduire de nouvelles matrices combinatoires: les tableaux bordelais. Le dernier chapitre est consacre a l'etude de l'arete-indice de transmission de certains graphes: line-graphs des graphes complets, graphes composes, graphes recursifs circulants, star-graphs
8
Renault, David. "Etude des graphes planaires cofinis selon leurs groupes de symétries." Bordeaux 1, 2004. http://www.theses.fr/2004BOR12922.
Full textAbstract:
Les graphes cofinis constituent une famille de graphes possédant un groupe de symétries non trivial, comme les graphes de Cayley ou les graphes sommet-transitifs. Lorsque ces graphes sont en plus planaires, ces symétries peuvent se traduire de manière simple grâce à des symétries du plan dans lequel les graphes sont dessinés. L'ensemble de ces symétries ou automorphismes permet alors de décrire globalement le graphe à l'aide de données géométriques locales, par des structures appelées schémas d'étiquetage. Dans cette thèse, nous étudions les groupes de symétries et décrivons les schémas d'étiquetage des graphes planaires cofinis possédant une représentation topologique simple : les graphes planaires localement finis. Nous montrons comment ces schémas permettent de caractériser le graphe et ses plongements. Cette analyse permet d'énu\-mérer cette famille des graphes planaires cofinis, en particulier lorsqu'ils sont de Cayley ou sommet-transitifs. A partir de ces résultats, nous nous intéressons à la structure des groupes d'automorphismes de cette famille de graphes. Des problèmes de la théorie combinatoire des groupes usuellement indécidables se trouvent devenir décidables dans notre cadre : c'est le cas en particulier des problèmes du mot, simple et généralisé. Les problèmes de décidabilité de la logique permettent de classifier ces graphes en deux grandes familles, selon leur largeur arborescente et la géométrie de leur plongement. Enfin, la question de l'extension de cette description à une famille de graphes plus généraux est étudiée. La classification de ces graphes en terme de bouts et de points d'accumulation dans les plongements permet d'obtenir des informations sur la forme que peuvent prendre les plongements des graphes planaires cofinis non localement finis. Nous discutons alors des difficultés d'extension de la méthode ``localement finie'' au cas général.
9
Guy, Jean-Pierre. "Groupes isomorphes au groupe de multiplication d'un quasigroupe." Toulouse 3, 1993. http://www.theses.fr/1993TOU30015.
Full textAbstract:
Probleme: soit g un groupe abstrait, est-il possible de construire un quasigroupe dont le groupe de multiplication est isomorphe a g? une reponse negative sera apportee pour les groupes hamiltoniens, de heineken-mohamed, des quaternions generalises et dicycliques d'ordre 4n. Une reponse positive sera apportee pour les groupes symetriques, alternes, diedraux, les groupes de mathieu de degre 11, 12 et 23, les groupes lineaires generaux et projectifs lineaires, certains p-groupes (semi-diedraux,. . . ), les groupes de coxeter de type bn. Le probleme pose pouvant se ramener a l'etude des groupes de multiplication de boucles, l'auteur construira des boucles commutatives, a l'aide de leurs translations a gauche, dont le groupe de multiplication est isomorphe soit au groupe (4,4|2,,2n+1) de degre 4n+2, soit au groupe (2,4,4;n+1) de degre 4n+4. Nous montrerons que certains d'entre eux sont transitifs minimaux, i. E. Sans sous groupe propre transitif. D'autre part, une boucle commutative dont le groupe de multiplication est isomorphe au p-sous groupe de sylow du groupe symetrique d'ordre p#2 sera construite par l'intermediaire de sa table de multiplication. Enfin, il sera montre que si les groupes abeliens, de fischer decentres, alternes sont representables en groupe de multiplication d'une boucle, une telle representation n'existe pas pour les groupes diedraux, les groupes de frobenius, les groupes de permutations dont le stabilisateur d'un element est de cardinal 1, 2 ou 3
10
Castel, Fabrice. "Représentations géométriques des groupes de tresses." Dijon, 2009. http://www.theses.fr/2009DIJOS020.
Full textAbstract:
Soit S la surface connexe orientable de genre g ayant b composantes de bords. On cherche à décrire l'ensemble des morphismes du groupe de tresses à n brins Bn où n est supérieur ou égal à 6, dans le mapping class group PMod(S) préservant chaque composante de bord, où g est inférieur ou égal à n/2 et b est quelconque. On prouve que sous ces conditions, les morphismes sont soit des morphismes cycliques (i. E. D'image cyclique), soit des transvections de morphismes de monodromie (i. E. à multiplication par un élément dans le centralisateur de l'image près, l'image d'un générateur standard de Bn est un twist de Dehn, et les images de deux générateurs standards consécutifs sont deux twists de Dehn le long de deux courbes s'intersectant en un point). En corollaire, on décrira l'ensemble des endomorphismes et celui des endomorphismes injectifs, le groupe d'automorphismes et celui des automorphismes extérieurs pour chacune des trois familles de groupes suivantes : les groupes de tresses Bn où n est supérieur ou égal à 6, les mapping class groups PMod(S) (préservant chaque composante de bord) et les mapping class groups Mod(S,dS) (préservant le bord point par point), pour tout g supérieur ou égal à 2 et b quelconque. On décrira également l'ensemble des morphismes entre groupes de tresses Bn et Bm avec m inférieur ou égal à n+1 et l'ensemble des morphismes entre mapping class groups de surfaces dont les genres diffèrent d'au plus un. Les techniques utilisées sont la classification de Nielsen-Thurston des difféomorphismes des surfaces, les actions de groupes et la théorie des graphesLet S be a connected orientable surface of genus g with b boundary components. We aim to describe the set of morphisms from the braid group Bn with n strands, where n is greater or equal to 6, to the mapping class group PMod(S) preserving globally each boundary component, where g is smaller or equal to n/2 and b is any positive integer. With these hypotheses, we prove that the morphisms are either cyclic (that is: their images are cyclic groups) or transvections of monodromy morphisms (that is: up to multiplication by an element lying in the centraliser of the image of the morphism, the image of a standard generator of Bn is a Dehn twist, and the images of two adjacent standard generators are two Dehn twists along two curves intersecting in one point. As a corollary, we describe the set of endomorphisms and the set of injective endomorphisms, the automorphisms group and the outer automorphisms group for each group of the following families : the braid groups Bn with n greater or equal to 6, the mapping class groups PMod(S) (where the boundary is preserved componentwise), the mapping class groups Mod(S,dS) (where the boundary is preserved pointwise), with g is greater or equal to 2 and b is any positive integer. We describe also the set of morphisms between two braid groups Bn and Bm with m smaller or equal to n+1 and the set of morphisms between two mapping class groups of surfaces whose genuses differ from at most one. The involved technics are Nielsen-Thurston classification of surface diffeomorphisms, group actions, and graph theory
Books on the topic "Graphes de groupes"
1
Kandasamy, W. B. Vasantha. Groups as graphs. Slatina, Judetul Olt, Romania: Editura CuArt, 2009.
Find full text
2
Ribes, Luis. Profinite Graphs and Groups. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61199-0.
Full text
3
Evans, Anthony B. Orthomorphism Graphs of Groups. Berlin, Heidelberg: Springer Berlin Heidelberg, 1992. http://dx.doi.org/10.1007/bfb0092363.
Full text
4
J, Dunwoody M., ed. Groups acting on graphs. Cambridge [England]: Cambridge University Press, 1989.
Find full text
6
Russell, Susan Jo. Sorting: Groups and graphs. Palo Alto, CA: Dale Seymour Publications, 1990.
Find full text
7
Mikov, Aleksandr. Generalized graphs and grammars. ru: INFRA-M Academic Publishing LLC., 2021. http://dx.doi.org/10.12737/1013698.
Full textAbstract:
The textbook deals with ordinary graphs and their generalizations-hypergraphs, hierarchical structures, geometric graphs, random and dynamic graphs. Graph grammars are considered in detail.
Meets the requirements of the federal state educational standards of higher education of the latest generation.
For master's students studying in the areas of the 02.00.00 group "Computer and Information Sciences", and can also be used in senior bachelor's courses and other areas in the field of computer science and computer engineering.
8
Jassim, Wadhah Saud. Pregroups and graphs of groups. Birmingham: University of Birmingham, 1991.
Find full text
9
Ceccherini-Silberstein, Tullio, Maura Salvatori, and Ecaterina Sava-Huss, eds. Groups, Graphs and Random Walks. Cambridge: Cambridge University Press, 2017. http://dx.doi.org/10.1017/9781316576571.
Full text
10
Groups, graphs, and trees: An introduction to the geometry of infinite groups. Cambridge: Cambridge University Press, 2008.
Find full textBook chapters on the topic "Graphes de groupes"
1
Kimoto, Kazufumi. "Generalized Group–Subgroup Pair Graphs." In International Symposium on Mathematics, Quantum Theory, and Cryptography, 169–85. Singapore: Springer Singapore, 2020. http://dx.doi.org/10.1007/978-981-15-5191-8_14.
Full textAbstract:
Abstract A regular finite graph is called a Ramanujan graph if its zeta function satisfies an analog of the Riemann Hypothesis. Such a graph has a small second eigenvalue so that it is used to construct cryptographic hash functions. Typically, explicit family of Ramanujan graphs are constructed by using Cayley graphs. In the paper, we introduce a generalization of Cayley graphs called generalized group–subgroup pair graphs, which are a generalization of group–subgroup pair graphs defined by Reyes-Bustos. We study basic properties, especially spectra of them.
2
Lubotzky, Alexander, and Benjamin Weiss. "Groups and expanders." In Expanding Graphs, 95–109. Providence, Rhode Island: American Mathematical Society, 1993. http://dx.doi.org/10.1090/dimacs/010/08.
Full text
3
Brouwer, Andries E., and Willem H. Haemers. "Groups and Graphs." In Universitext, 93–99. New York, NY: Springer New York, 2011. http://dx.doi.org/10.1007/978-1-4614-1939-6_6.
Full text
4
Brown, Nathanial, and Narutaka Ozawa. "Groups and graphs." In Graduate Studies in Mathematics, 471–78. Providence, Rhode Island: American Mathematical Society, 2008. http://dx.doi.org/10.1090/gsm/088/22.
Full text
5
Beck, Matthias, and Ross Geoghegan. "Groups and Graphs." In The Art of Proof, 151–60. New York, NY: Springer New York, 2010. http://dx.doi.org/10.1007/978-1-4419-7023-7_18.
Full text
6
Xu, Junming. "Graphs and Groups." In Network Theory and Applications, 279–308. Boston, MA: Springer US, 2003. http://dx.doi.org/10.1007/978-1-4419-8698-6_7.
Full text
7
Ribes, Luis. "Profinite Graphs." In Profinite Graphs and Groups, 29–61. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61199-0_2.
Full text
8
Ribes, Luis. "Subgroups of Fundamental Groups of Graphs of Groups." In Profinite Graphs and Groups, 223–35. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61199-0_7.
Full text
9
Schellwat, Holger. "Highly expanding graphs obtained from dihedral groups." In Expanding Graphs, 117–23. Providence, Rhode Island: American Mathematical Society, 1993. http://dx.doi.org/10.1090/dimacs/010/10.
Full text
10
Loos, Ottmar, and Erhard Neher. "Jordan Graphs." In Steinberg Groups for Jordan Pairs, 184–264. New York, NY: Springer New York, 2019. http://dx.doi.org/10.1007/978-1-0716-0264-5_4.
Full textConference papers on the topic "Graphes de groupes"
1
Shai, Offer. "Topological Synthesis of All 2D Mechanisms Through Assur Graphs." In ASME 2010 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2010. http://dx.doi.org/10.1115/detc2010-28926.
Full textAbstract:
It is well known that every planar kinematical linkage can be decomposed into basic topological structures referred as Assur Groups. A new reformulation of Assur Group concept into the terminology of rigidity theory, as Assur Graphs, has yielded the development of new theorems and methods. The paper reports on an algorithm for systematic construction of Assur Graph classes, termed fundamental Assur Graphs. From each fundamental Assur Graph it is possible to derive an infinite set of different Assur Graphs. This mapping algorithm is proved to be complete and sound, i.e., all the Assur Graphs appear in the map and each graph in the map is an Assur Graph. Once we possess the mapping of all the Assur Graphs, all valid kinematical linkage topologies can be constructed through various Assur Graph compositions.
2
Hahn, Elad, Adnan Sljoka, and Andreas Mueller. "Applications of Constraint Graphs and Assur Groups in Mechanism Analysis and Synthesis." In ASME 2017 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/detc2017-67925.
Full textAbstract:
Assur groups and correspondingly Assur graphs have key attributes that make them important for the analysis and synthesis of linkages. The topology of linkages (more precisely the existence of constraints between links) in general can be represented by various types of constraint graphs. The concept of Assur graphs applies to any such graph and thus their peculiar features can be exploited. Despite of these potential benefits the relevant methods and tools are scattered in the literature. The aim of this paper is to provide an overview of the use of constraint graphs including recent results on the construction of Assur graphs.
3
Zhou, Kaixiong, Qingquan Song, Xiao Huang, Daochen Zha, Na Zou, and Xia Hu. "Multi-Channel Graph Neural Networks." In Twenty-Ninth International Joint Conference on Artificial Intelligence and Seventeenth Pacific Rim International Conference on Artificial Intelligence {IJCAI-PRICAI-20}. California: International Joint Conferences on Artificial Intelligence Organization, 2020. http://dx.doi.org/10.24963/ijcai.2020/188.
Full textAbstract:
The classification of graph-structured data has be-come increasingly crucial in many disciplines. It has been observed that the implicit or explicit hierarchical community structures preserved in real-world graphs could be useful for downstream classification applications. A straightforward way to leverage the hierarchical structure is to make use the pooling algorithms to cluster nodes into fixed groups, and shrink the input graph layer by layer to learn the pooled graphs.However, the pool shrinking discards the graph details to make it hard to distinguish two non-isomorphic graphs, and the fixed clustering ignores the inherent multiple characteristics of nodes. To compensate the shrinking loss and learn the various nodes’ characteristics, we propose the multi-channel graph neural networks (MuchGNN). Motivated by the underlying mechanisms developed in convolutional neural networks, we define the tailored graph convolutions to learn a series of graph channels at each layer, and shrink the graphs hierarchically to en-code the pooled structures. Experimental results on real-world datasets demonstrate the superiority of MuchGNN over the state-of-the-art methods.
4
Hahn, Elad, and Offer Shai. "A Single Universal Construction Rule for the Structural Synthesis of Mechanisms." In ASME 2016 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/detc2016-59133.
Full textAbstract:
In the field of structural synthesis of mechanisms several synthesis methods have been developed using different approaches. One of the more interesting approaches was that of bottom-up construction via the combination of modular structural groups, known as Assur groups. This approach is combined with new graph representations of mechanisms taken from rigidity theory, capable of representing all the different types of planar and spatial mechanisms. With the strong mathematical base of rigidity theory, a new synthesis method is proposed based on Assur groups, which are reformulated in terms of graph theory and renamed Assur Graphs. Using a single universal construction rule, Assur Graphs of different types and of any number of links are constructed, creating a complete set of building blocks for the synthesis of feasible mechanisms. As its name implies, the single universal construction is applicable for mechanisms of all types of joints and links, for planar or spatial motion.
5
Navakas, Robertas, and Algis Džiugys. "A community detection method for network structure analysis of force chains in granular medium in a rotating drum." In The 13th international scientific conference “Modern Building Materials, Structures and Techniques”. Vilnius Gediminas Technical University, 2019. http://dx.doi.org/10.3846/mbmst.2019.079.
Full textAbstract:
We analyze the motion of granular matter in a partially filled drum rotating around the horizontal axis. The motion of granular medium is simulated using the discrete element model (DEM). As the drum rotates, the free surface sloping angle changes periodically as it attains the limit repose angle leading to an avalanche, after which its value is reduced to below the repose angle. Systems of this type are of interest from both theoretical and application viewpoints: similar setups are used in industry, such as rotary kilns and mixers; besides, dynamics of granular matter leads to macroscopic effects, such as segregation and emergence of patterns. Observable macroscopic effects depend largely on the underlying structure of force chains arising from pairwise mechanical contacts between the particles. Discrete element simulations produce the data for each individual particle: position, translational and rotational velocity, force vector between the interacting particle pairs. These data about the microscopic state must be processed to obtain the observable macroscopic states. Particle configurations at each time moment available from DEM simulations can be represented as graphs: each particle is represented as a graph vertex, the vertex pairs are connected by edges if the respective particle pairs are in contact, and the edge weights are proportional to the interaction force. After the graph for a particle state is created, the algorithms of the graph analysis can be applied to analyze the corresponding state of granular matter. Among such algorithms, we use the community detection algorithms to analyse the emergence of force groups among the particles, i.e., the groups of particles that have stronger mechanical forces among the particles in the group than the forces with particles that do not belong to the given group. Such groups are structures of larger scale than the usual force chains. Distribution of group sizes (number of particles belonging to the group) and their positions depend on the rotation velocities of the drum; in turn, they influence the variation of the repose angle and the process of the avalanches. We report the relations between the characteristics of the detected force groups and the observable effects in the granular matter obtained by DEM simulations.
6
Yi, Lu, and Tatu Leinonen. "Solution of Topology Embryonic Graph and Topology Graph for Unified Planar-Spatial Mechanisms." In ASME 2003 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/detc2003/dfm-48167.
Full textAbstract:
An analysis matrix approach for solving an isomeric topology embryonic graph and a digital group approach for solving an isomeric topology graph of a unified planar-spatial mechanism are presented and the relative theory is discussed. Firstly, all binary links are removed from each acceptable linkage system with different degrees of freedom, many analysis matrixes are constructed, and many topology embryonic graphs of the mechanism are derived. Secondly, from an acceptable multi-element link combination of planar or spatial mechanisms, a rule for determining the isomeric topology embryonic graphs and an unreasonable topology embryonic graph is obtained. Thirdly, by considering the degree of freedom of the mechanism and the configuration of a planar or spatial mechanism, the number of binary links is determined. Finally, all removed binary links are rearranged systematically back into an isomeric topology embryonic graph, and the acceptable topology graphs of the mechanism are derived by using a digital group approach. Some illustrations show that the two approaches are simple and effective tools and can be employed to synthesize both planar and spatial mechanisms.
7
Kauffman, Louis H., and Samuel J. Lomonaco, Jr. "Quantizing knots, groups and graphs." In SPIE Defense, Security, and Sensing, edited by Eric Donkor, Andrew R. Pirich, and Howard E. Brandt. SPIE, 2011. http://dx.doi.org/10.1117/12.882567.
Full text
8
Kabanov, Vladislav, Theodore E. Simos, George Psihoyios, and Ch Tsitouras. "Graphs and Transitive Permutation Groups." In ICNAAM 2010: International Conference of Numerical Analysis and Applied Mathematics 2010. AIP, 2010. http://dx.doi.org/10.1063/1.3498638.
Full text
9
Gopalakrishnan, Mini, and N. Naga Maruthi Kumari. "Generator graphs for cyclic groups." In THE 11TH NATIONAL CONFERENCE ON MATHEMATICAL TECHNIQUES AND APPLICATIONS. AIP Publishing, 2019. http://dx.doi.org/10.1063/1.5112304.
Full text
10
Swathi, V. V., and M. S. Sunitha. "Square graphs of finite groups." In INTERNATIONAL CONFERENCE ON COMPUTATIONAL SCIENCES-MODELLING, COMPUTING AND SOFT COMPUTING (CSMCS 2020). AIP Publishing, 2021. http://dx.doi.org/10.1063/5.0045744.
Full textReports on the topic "Graphes de groupes"
1
Zhai, Liangliang, and Xuanlong Ma. Perfect Codes in Proper Order Divisor Graphs of Finite Groups. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, December 2020. http://dx.doi.org/10.7546/crabs.2020.12.04.
Full text
2
Deryagina, Madina, and Ilia Mednykh Mednykh. On the Jacobian Group for Möbius Ladder and Prism Graphs. GIQ, 2014. http://dx.doi.org/10.7546/giq-15-2014-117-126.
Full text
3
Rosenfeld, A. ARC Colorings, Partial Path Groups, and Parallel Graph Contractions. Fort Belvoir, VA: Defense Technical Information Center, July 1985. http://dx.doi.org/10.21236/ada158918.
Full text
4
Liu, Xiu, and Xuanlong Ma. The Order Divisor Graph of a Finite Group. "Prof. Marin Drinov" Publishing House of Bulgarian Academy of Sciences, March 2020. http://dx.doi.org/10.7546/crabs.2020.03.06.
Full text
5
Nic Daeid, Niamh, Heather Doran, Lucina Hackman, and Pauline Mack. The Curse of the Burial Dagger Teacher Materials. University of Dundee, September 2021. http://dx.doi.org/10.20933/100001220.
Full textAbstract:
The Curse of the Burial Dagger is an interactive graphic novel murder mystery, created by the Leverhulme Research Centre for Forensic Science and digital story studio Fast Familiar. Players use maths, logic and critical reasoning skills to assist Susie uncover different types of forensic evidence and weigh up contrasting hypotheses. Can they uncover the events leading up to Lord Hamilton’s death and deduce how he died…before the curse strikes again? These documents are the Teacher/Group lead pack which contain additional resources including: • The Teacher/Group Lead Pack – Teacher walk through – Factsheet – What is Forensic Science? – Factsheet – What is a hypothesis? – Marzipan Calculation – Factsheet and activity – Fingerprint Analysis – Activity – Chromatography investigation • Printable completion certificate • Printable Note paper and fact-sheet
6
Schulz, Jan, Daniel Mayerhoffer, and Anna Gebhard. A Network-Based Explanation of Perceived Inequality. Otto-Friedrich-Universität, 2021. http://dx.doi.org/10.20378/irb-49393.
Full textAbstract:
Across income groups and countries, the public perception of economic inequality and many other macroeconomic variables such as inflation or unemployment rates is spectacularly wrong. These misperceptions have far-reaching consequences, as it is perceived inequality, not actual inequality informing redistributive preferences. The prevalence of this phenomenon is independent of social class and welfare regime, which suggests the existence of a common mechanism behind public perceptions. We propose a network-based explanation of perceived inequality building on recent advances in random geometric graph theory. The literature has identified several stylised facts on how individual perceptions respond to actual inequality and how these biases vary systematically along the income distribution. Our generating mechanism can replicate all of them simultaneously. It also produces social networks that exhibit salient features of real-world networks; namely, they cannot be statistically distinguished from small-world networks, testifying to the robustness of our approach. Our results, therefore, suggest that homophilic segregation is a promising candidate to explain inequality perceptions with strong implications for theories of consumption behaviour.
7
Wells, Aaron, Tracy Christopherson, Gerald Frost, Matthew Macander, Susan Ives, Robert McNown, and Erin Johnson. Ecological land survey and soils inventory for Katmai National Park and Preserve, 2016–2017. National Park Service, September 2021. http://dx.doi.org/10.36967/nrr-2287466.
Full textAbstract:
This study was conducted to inventory, classify, and map soils and vegetation within the ecosystems of Katmai National Park and Preserve (KATM) using an ecological land survey (ELS) approach. The ecosystem classes identified in the ELS effort were mapped across the park, using an archive of Geo-graphic Information System (GIS) and Remote Sensing (RS) datasets pertaining to land cover, topography, surficial geology, and glacial history. The description and mapping of the landform-vegetation-soil relationships identified in the ELS work provides tools to support the design and implementation of future field- and RS-based studies, facilitates further analysis and contextualization of existing data, and will help inform natural resource management decisions. We collected information on the geomorphic, topographic, hydrologic, pedologic, and vegetation characteristics of ecosystems using a dataset of 724 field plots, of which 407 were sampled by ABR, Inc.—Environmental Research and Services (ABR) staff in 2016–2017, and 317 were from existing, ancillary datasets. ABR field plots were located along transects that were selected using a gradient-direct sampling scheme (Austin and Heligers 1989) to collect data for the range of ecological conditions present within KATM, and to provide the data needed to interpret ecosystem and soils development. The field plot dataset encompassed all of the major environmental gradients and landscape histories present in KATM. Individual state-factors (e.g., soil pH, slope aspect) and other ecosystem components (e.g., geomorphic unit, vegetation species composition and structure) were measured or categorized using standard classification systems developed for Alaska. We described and analyzed the hierarchical relationships among the ecosystem components to classify 92 Plot Ecotypes (local-scale ecosystems) that best partitioned the variation in soils, vegetation, and disturbance properties observed at the field plots. From the 92 Plot Ecotypes, we developed classifications of Map Ecotypes and Disturbance Landscapes that could be mapped across the park. Additionally, using an existing surficial geology map for KATM, we developed a map of Generalized Soil Texture by aggregating similar surficial geology classes into a reduced set of classes representing the predominant soil textures in each. We then intersected the Ecotype map with the General-ized Soil Texture Map in a GIS and aggregated combinations of Map Ecotypes with similar soils to derive and map Soil Landscapes and Soil Great Groups. The classification of Great Groups captures information on the soil as a whole, as opposed to the subgroup classification which focuses on the properties of specific horizons (Soil Survey Staff 1999). Of the 724 plots included in the Ecotype analysis, sufficient soils data for classifying soil subgroups was available for 467 plots. Soils from 8 orders of soil taxonomy were encountered during the field sampling: Alfisols (<1% of the mapped area), Andisols (3%), Entisols (45%), Gelisols (<1%), Histosols (12%), Inceptisols (22%), Mollisols (<1%), and Spodosols (16%). Within these 8 Soil Orders, field plots corresponded to a total of 74 Soil Subgroups, the most common of which were Typic Cryaquents, Typic Cryorthents, Histic Cryaquepts, Vitrandic Cryorthents, and Typic Cryofluvents.
8
Financial Stability Report - Second Semester of 2020. Banco de la República de Colombia, March 2021. http://dx.doi.org/10.32468/rept-estab-fin.sem2.eng-2020.
Full textAbstract:
The Colombian financial system has not suffered major structural disruptions during these months of deep economic contraction and has continued to carry out its basic functions as usual, thus facilitating the economy's response to extreme conditions. This is the result of the soundness of financial institutions at the beginning of the crisis, which was reflected in high liquidity and capital adequacy indicators as well as in the timely response of various authorities. Banco de la República lowered its policy interest rates 250 points to 1.75%, the lowest level since the creation of the new independent bank in 1991, and provided ample temporary and permanent liquidity in both pesos and foreign currency. The Office of the Financial Superintendent of Colombia, in turn, adopted prudential measures to facilitate changes in the conditions for loans in effect and temporary rules for rating and loan-loss provisions. Finally, the national government expanded the transfers as well as the guaranteed credit programs for the economy. The supply of real credit (i.e. discounting inflation) in the economy is 4% higher today than it was 12 months ago with especially marked growth in the housing (5.6%) and commercial (4.7%) loan portfolios (2.3% in consumer and -0.1% in microloans), but there have been significant changes over time. During the first few months of the quarantine, firms increased their demands for liquidity sharply while consumers reduced theirs. Since then, the growth of credit to firms has tended to slow down, while consumer and housing credit has grown. The financial system has responded satisfactorily to the changes in the respective demands of each group or sector and loans may grow at high rates in 2021 if GDP grows at rates close to 4.6% as the technical staff at the Bank expects; but the forecasts are highly uncertain. After the strict quarantine implemented by authorities in Colombia, the turmoil seen in March and early April, which was evident in the sudden reddening of macroeconomic variables on the risk heatmap in Graph A,[1] and the drop in crude oil and coal prices (note the high volatility registered in market risk for the region on Graph A) the local financial markets stabilized relatively quickly. Banco de la República’s credible and sustained policy response played a decisive role in this stabilization in terms of liquidity provision through a sharp expansion of repo operations (and changes in amounts, terms, counterparties, and eligible instruments), the purchases of public and private debt, and the reduction in bank reserve requirements. In this respect, there is now abundant aggregate liquidity and significant improvements in the liquidity position of investment funds. In this context, the main vulnerability factor for financial stability in the short term is still the high degree of uncertainty surrounding loan quality. First, the future trajectory of the number of people infected and deceased by the virus and the possible need for additional health measures is uncertain. For that reason, there is also uncertainty about the path for economic recovery in the short and medium term. Second, the degree to which the current shock will be reflected in loan quality once the risk materializes in banks’ financial statements is uncertain. For the time being, the credit risk heatmap (Graph B) indicates that non-performing and risky loans have not shown major deterioration, but past experience indicates that periods of sharp economic slowdown eventually tend to coincide with rises in non-performing loans: the calculations included in this report suggest that the impact of the recession on credit quality could be significant in the short term. This is particularly worrying since the profitability of credit establishments has been declining in recent months, and this could affect their ability to provide credit to the real sector of the economy. In order to adopt a forward-looking approach to this vulnerability, this Report presents several stress tests that evaluate the resilience of the liquidity and capital adequacy of credit institutions and investment funds in the event of a hypothetical scenario that seeks to simulate an extreme version of current macroeconomic conditions. The results suggest that even though there could be strong impacts on the credit institutions’ volume of credit and profitability under such scenarios, aggregate indicators of total and core capital adequacy will probably remain at levels that are above the regulatory limits over the horizon of a year. At the same time, the exercises highlight the high capacity of the system's liquidity to face adverse scenarios. In compliance with its constitutional objectives and in coordination with the financial system's security network, Banco de la República will continue to closely monitor the outlook for financial stability at this juncture and will make the decisions that are necessary to ensure the proper functioning of the economy, facilitate the flow of sufficient credit and liquidity resources, and further the smooth operation of the payment systems. Juan José Echavarría Governor
9
Monetary Policy Report - January 2021. Banco de la República de Colombia, March 2021. http://dx.doi.org/10.32468/inf-pol-mont-eng.tr1.-2021.
Full textAbstract:
Macroeconomic Summary Overall inflation (1.61%) and core inflation (excluding food and regulated items) (1.11%) both declined beyond the technical staff’s expectations in the fourth quarter of 2020. Year-end 2021 forecasts for both indicators were revised downward to 2.3% and 2.1%, respectively. Market inflation expectations also fell over this period and suggested inflation below the 3% target through the end of this year, rising to the target in 2022. Downward pressure on inflation was more significant in the fourth quarter than previously projected, indicating weak demand. Annual deceleration among the main groups of the consumer price index (CPI) was generalized and, except for foods, was greater than projected in the October report. The CPI for goods (excluding foods and regulated items) and the CPI for regulated items were subject to the largest decelerations and forecasting discrepancies. In the first case, this was due in part to a greater-than-expected effect on prices from the government’s “VAT-fee day” amid weak demand, and from the extension of some price relief measures. For regulated items, the deceleration was caused in part by unanticipated declines in some utility prices. Annual change in the CPI for services continued to decline as a result of the performance of those services that were not subject to price relief measures, in particular. Although some of the overall decline in inflation is expected to be temporary and reverse course in the second quarter of 2021, various sources of downward pressure on inflation have become more acute and will likely remain into next year. These include ample excesses in capacity, as suggested by the continued and greater-than-expected deceleration in core inflation indicators and in the CPI for services excluding price relief measures. This dynamic is also suggested by the minimal transmission of accumulated depreciation of the peso on domestic prices. Although excess capacity should fall in 2021, the decline will likely be slower than projected in the October report amid additional restrictions on mobility due to a recent acceleration of growth in COVID-19 cases. An additional factor is that low inflation registered at the end of 2020 will likely be reflected in low price adjustments on certain indexed services with significant weight in the CPI, including real estate rentals and some utilities. These factors should keep inflation below the target and lower than estimates from the previous report on the forecast horizon. Inflation is expected to continue to decline to levels near 1% in March, later increasing to 2.3% at the end of 2021 and 2.7% at year-end 2022 (Graph 1.1). According to the Bank’s most recent survey, market analysts expect inflation of 2.7% and 3.1% in December 2021 and 2022, respectively. Expected inflation derived from government bonds was 2% for year-end 2021, while expected inflation based on bonds one year forward from that date (FBEI 1-1 2022) was 3.2%.