306,672 research outputs found
Optimizing the trade-off between number of cops and capture time in Cops and Robbers
No full textThe cop throttling number thc(G) of a graph G for the game of Cops and Robbers is the minimum of k + captk (G), where k is the number of cops and captk (G) is the minimum number of rounds needed for k cops to capture the robber on G over all possible games in which both players play optimally. In this paper, we construct a family of graphs having thc(G) = Ω n²/³ , establish a sublinear upper bound on the cop throttling number, and show that the cop throttling number of chordal graphs is O( n). We also introduce the product cop throttling number th×(G) as a parameter that minimizes the person-hours used by the cops. This parameter extends the notion of speed-up that has been studied in the context of parallel processing and network decontamination. We establish bounds on the product cop throttling number in terms of the cop throttling number, characterize graphs with low product cop throttling number, and show that for a chordal graph G, th×(G) = 1 + rad(G).This article is published as Bonato, Anthony, Jane Breen, Boris Brimkov, Joshua Carlson, Sean English, Jesse Geneson, Leslie Hogben, K. E. Perry, and Carolyn Reinhart. "Optimizing the trade-off between number of cops and capture time in Cops and Robbers." Journal of Combinatorics 13, no. 1 (2022): 79-103. https://dx.doi.org/10.4310/JOC.2022.v13.n1.a
Optimizing the trade-off between number of cops and capture time in Cops and Robbers
No full textThe cop throttling number thc(G) of a graph G for the game of Cops and Robbers is the minimum of k+captk(G), where k is the number of cops and captk(G) is the minimum number of rounds needed for k cops to capture the robber on G over all possible games in which both players play optimally. In this paper, we construct a family of graphs having thc(G)=Ω(n2/3), establish a sublinear upper bound on the cop throttling number, and show that the cop throttling number of chordal graphs is O(n−−√). We also introduce the product cop throttling number th×c(G) as a parameter that minimizes the person-hours used by the cops. This parameter extends the notion of speed-up that has been studied in the context of parallel processing and network decontamination. We establish bounds on the product cop throttling number in terms of the cop throttling number, characterize graphs with low product cop throttling number, and show that for a chordal graph G, th×c=1+rad(G).This is a pre-print of the article Bonato, Anthony, Jane Breen, Boris Brimkov, Joshua Carlson, Sean English, Jesse Geneson, Leslie Hogben, K. E. Perry, and Carolyn Reinhart. "Optimizing the trade-off between number of cops and capture time in Cops and Robbers." arXiv preprint arXiv:1903.10087v2 (2019). Posted with permission. </p
Fatores críticos de sucesso à manutenção de comunidades de prática e suas dimensões de análise
No full textDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia e Gestão do Conhecimento, Florianópolis, 2012Esta pesquisa almejou identificar os fatores críticos de sucesso (FCS) à manutenção das Comunidades de Prática que estabelecem relação com as dimensões de análise das Comunidades. Para tanto, realizou-se uma busca sistemática da literatura em que emergiram 112 FCS à manutenção das CoPs. Concomitante, identificaram-se na literatura algumas dimensões de análise para Comunidades, tais como: individual, organizacional, liderança, comunidade, cognitiva, tecnológica e econômica. Em virtude das características de alguns dos fatores revelados, e pela ausência de dimensões que os contemplassem, outras três dimensões foram propostas: a relações de poder, a cultural e a operacional. Após o levantamento dos FCS e das dimensões, alocaram-se os fatores às dimensões que melhor lhes representavam, além de respeitar a indicação dos autores quando assim o fizeram, resultando em quadros de referência por dimensão e seus respectivos FCS. Em seguida, foi possível verificar que alguns fatores transitavam entre duas dimensões de análise, o que se denominou de interseção de dimensões diversas. Por fim, chegou-se aos 28 fatores críticos de sucesso à manutenção das CoPs e suas dimensões de análise, circunstância que possibilitou a criação de um quadro-síntese com tais informações. Respeitando a caracterização da pesquisa quanto aos fins, indica-se que o primeiro resultado é de origem aplicada, porquanto possui como base de motivação a resolução de problemas concretos referente à gestão das CoPs, qual seja: a identificação dos fatores críticos de sucesso à manutenção das CoPs, e suas vinculações às dimensões de análise. O segundo repousa no campo da contribuição teórica, visto que pode auxiliar como ponto de partida para investigações futuras sobre a temática.Abstract : This research sought to identify the critical success factors (CSFs) for the maintenance of Communities of Practice that establish relationship with the Communities# dimensions of analysis. Therefore, it was carried out a systematic search of literature where 112 CSFs emerged for the maintenance of CoPs. Concomitantly, it was identified in the literature some analysis dimensions for Communities such as: individual, organizational, leadership, community, cognitive, technological and economic. Because of the characteristics of some of the factors revealed, and due to the absence of dimensions that behold them, three other dimensions were proposed: the power relations, as well as the cultural and the operational. After surveying the CSFs and dimensions, the factors were allocated to the dimensions that best represented them, besides respecting the suggestion of the authors when they did so, resulting in charts of reference by dimension and respective CSFs. Then it was possible to find that some factors were transiting between two dimensions of analysis, which was so called intersection of varied dimensions. Finally, it was reached 28 critical success factors for the maintenance of CoPs and their analysis dimensions, a circumstance that enabled the creation of a summary table with such information. Having regard to the characterization as to the purposes, it is indicated that the first result is of applied origin, since it has as a basis of motivation the resolution of specific problems regarding the management of CoPs, namely, the identification of critical success factors for the maintaining of CoPs, and their linkages to the analysis dimensions. The second result lies in the field of theoretical contribution, since it can help as a starting point for future research on the topic
Cops against a cheating robber
No full textWe investigate a cheating robot version of Cops and Robber, first introduced by Huggan and Nowakowski, where both the cops and the robber move simultaneously, but the robber is allowed to react to the cops\u27 moves. For conciseness, we refer to this game as Cops and Cheating Robot. The cheating robot number for a graph is the fewest number of cops needed to win on the graph. We introduce a new parameter for this variation, called the push number, which gives the value for the minimum number of cops that move onto the robber\u27s vertex given that there are a cheating robot number of cops on the graph. After producing some elementary results on the push number, we use it to give a relationship between Cops and Cheating Robot and Surrounding Cops and Robbers. We investigate the cheating robot number for planar graphs and give a tight bound for bipartite planar graphs. We show that determining whether a graph has a cheating robot number at most fixed can be done in polynomial time. We also obtain bounds on the cheating robot number for strong and lexicographic products of graphs.27 pages, 4 figure
CoPS - Checker of Persistent Security
No full textCoPS is an automatic checker of multilevel system security properties. CoPS can be used to check three different bisimulation-based non-interference properties for systems expressed as terms of the Security Process Algebra (SPA) language. The considered properties are persistent, in the sense that they are preserved at each execution step. Moreover, they imply the Bisimulation-based Non Deducibility on Composition (BNDC) property, whose decidability is still an open problem
Mechanisms for AAA and QoS Interaction
No full textProceedings of Third IEEE Workshop on Applications and Services in Wireless Networks, ASWN 2003. Bern, Switzerland, July 2-4, 2003.The interaction between Authentication, Authorization and Accounting (AAA) systems and the Quality of Service (QoS) infrastructure is to become a must in the near future. This interaction will allow rich control and management of both users and networks. DIAMETER and DiffServ are likely to turn into the future standards in AAA and QoS systems, but they are not designed to interact with each other. To face this, we propose a new Diameter-Diffserv interaction model and describe the Application Specific Module (ASM) implemented to allow this interaction. The ASM has been implemented and tested in a complete AAA-QoS IPv6 scenario
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Structural health assessment of communities of practice (CoPs)
No full textPurpose
– This paper aims to provide organizational knowledge management teams with a new metric, the bottleneck impact score (BIS), a valuable tool for evaluating the structural health of communities of practice (CoPs), by detecting the seriousness and pervasiveness of the bottlenecks occurring in knowledge-sharing activities among CoP members.
Design/methodology/approach
– This paper uses the social network analysis method to analyze the activities of organizational members in CoPs and classify organizational members into four types based on their degree of involvement in knowledge creation and consumption. CoPs are also categorized into four types based on the proportion of member types they contain to identify the characteristics of CoP member types and of CoP types.
Findings
– Data analysis of the knowledge-sharing activities of 4,414 members from 59 CoPs within one of the largest steel manufacturing companies finds that few CoPs are active in both knowledge creating and consuming and that most CoPs suffer from the insufficient participation of their most experienced employees and experts and hence are vulnerable to master–apprentice and knowledge drain risks.
Originality/value
– The proposed BIS metric successfully quantifies the seriousness and pervasiveness of such structural risks and thus can help management teams take preventive action to reduce the identified structural risks.112ssciscopu
-Hyperopic Cops and Robber
No full textA generalization of hyperopic cops and robber, analogous to the -visibility cops and robber, is introduced in this paper. For a positive integer the -hyperopic game of cops and robber is defined similarly as the usual cops and robber game, but with the robber being omniscient and invisible to the cops that are at distance at most away from the robber. The cops win the game if, after a finite number of rounds, a cop occupies the same vertex as robber. Otherwise, robber wins. The minimum number of cops needed to win the game on a graph is the -hyperopic cop number of .
In addition to basic properties of the new invariant, cop-win graphs are characterized and a general upper bound in terms of the matching number of the graph is given. The invariant is also studied on trees where the upper bounds mostly depend on the relation between and the diameter of the tree. It is also proven that the 2-hyperopic cop number of outerplanar graphs is at most 2 and an upper bound in terms of the number of vertices of the graph is presented for .20 pages, 4 figure
Cops and Attacking Robbers with Cycle Constraints
No full textThis paper considers the Cops and Attacking Robbers game, a variant of Cops and Robbers, where the robber is empowered to attack a cop in the same way a cop can capture the robber. In a graph , the number of cops required to capture a robber in the Cops and Attacking Robbers game is denoted by \attCop(G). We characterise the triangle-free graphs with \attCop(G) \leq 2 via a natural generalisation of the cop-win characterisation by Nowakowski and Winkler \cite{nowakowski1983vertex}. We also prove that all bipartite planar graphs have \attCop(G) \leq 4 and show this is tight by constructing a bipartite planar graph with \attCop(G) = 4. Finally we construct non-isomorphic graphs of order with \attCop(H) = 6 and \cop(H)=3. This provides the first example of a graph with \attCop(H) - \cop(H) \geq 3 extending work by Bonato, Finbow, Gordinowicz, Haidar, Kinnersley, Mitsche, Prałat, and Stacho \cite{bonato2014robber}. We conclude with a list of conjectures and open problems.25 pages, 5 figure
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