995,385 research outputs found

    Topology recognition with advice

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    In topology recognition, each node of an anonymous network has to deterministically produce an isomorphic copy of the underlying graph, with all ports correctly marked. This task is usually unfeasible without any a priori information. Such information can be provided to nodes as advice. An oracle knowing the network can give a (possibly different) string of bits to each node, and all nodes must reconstruct the network using this advice, after a given number of rounds of communication. During each round each node can exchange arbitrary messages with all its neighbors and perform arbitrary local computations. The time of completing topology recognition is the number of rounds it takes, and the size of advice is the maximum length of a string given to nodes. We investigate tradeoffs between the time in which topology recognition is accomplished and the minimum size of advice that has to be given to nodes. We provide upper and lower bounds on the minimum size of advice that is sufficient to perform topology recognition in a given time, in the class of all graphs of size nn and diameter DαnD\le \alpha n, for any constant α<1\alpha< 1. In most cases, our bounds are asymptotically tight

    Advice seeking network structures and the learning organization

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    Organizational learning can be described as a transfer of individuals’ cognitive mental models to shared mental models. Employees, seeking the same colleagues for advice, are structurally equivalent, and the aim of the paper is to study if the concept can act as a conduit for organizational learning. It is argued that the mimicking of colleagues’ advice seeking structures will induce structural equivalence and transfer the accuracy of individuals’ cognitive mental models to shared mental models. Taking a dyadic level of analysis authors revisit a classical case and present novel data analyses.The empirical results indicate that the mimicking of advice seeking structures can alter cognitive accuracy. It is discussed the findings’ implications for organization learning theory and practice, addressed the study’s limitations, and suggested avenues for future research

    Final evaluation of the growth investment network East Midlands

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    A summative evaluation of the delivery of the Growth Investment Network from October 2004 to March 2010, a network of specialists established by emda to co-ordinate investment activity, collaborate on business deals and provide advice and support to entrepreneurs. The report includes both an overview of Strategic Added Value (SAV) and overall economic impact

    IDEAS project - Professional advice network study in Ethiopia

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    The IDEAS project sought to improve the health and survival of mothers and babies through generating evidence to inform policy and practice. This collection contains quantitative data, collection tools and documentation associated with a social network analysis study of the professional advice networks used by health care workers in Ethiopia. The cross-sectional, mixed-methods observational network study compared professional advice networks of 160 healthcare workers in 8 primary health care units (PHCUs) across four regions of Ethiopia; Amhara, Oromia, SNNP and Tigray. PHCUs include a health centre and typically 5 satellite health posts. Data captured included health care worker advice seeking and giving for the provision of four areas along the continuum of maternal and newborn care: antenatal care, childbirth care, postnatal care and newborn care. Additional information captured regarded professional advice exchange beyond the roster of health care workers in the PHCU. Network metrics were qualitatively compared to continuum of care coverage data as a secondary analysis. Twenty semi-structured qualitative interviews of purposively selected subjects followed the collection of quantitative network data to interpret and explain network roles and patterns observed

    Drivers’ Response to In-Vehicle Route Guidance Information Systems: An Experiemnt with a Mock-Up Guidance System.

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    The paper reports an exploratory study, using an unusual technique to investigate drivers' response to in-vehicle route guidance information systems. Eighteen drivers were recruited, and asked to make a series of three trips in an unfamiliar area. Each driver was given turning advice, via a speech synthesiser, on one of these trips. This advice was based on average traffic conditions for the time of day. Unbeknown to the drivers, the advice was in fact triggered by the experimenter, who was riding as a back-seat passenger. Details were kept of times and routes taken with and without guidance, and with different levels of network familiarity. Records were also kept (using questionnaires and video and audio recording) of planning and route-following strategies. As expected, both receipt of guidance and even very rudimentary network familiarity resulted in reduced journey times, and routes closer to the guidance recommendations. The study indicated that factors including the directness of possible routes, their perceived complexity, and familiarity all affect route choice, but to different extents for different individuals and under different circumstances. Error was shown to be important in determining the route actually followed when guidance was withheld. The study showed that giving in-vehicle guidance using the mock-up technique described is practicable, and does influence drivers' route-choice and route-following behaviour. A possible future study is outlined, aimed at identifying the determinants of the drivers' level of compliance with advice when they believe that advice is based on real-time traffic information

    CAN OPINION BE STABLE IN AN OPEN NETWORK WITH HIERARCHY?AN AGENT-BASED MODEL OF THE COMMERCIAL COURT OF PARIS

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    The co-evolution of social networks and opinion formation has received increasing attention in recent years. As a contribution to the growing literature on this topic, we explore connections between empirical data representing the advice network of judges at the Commercial Court in Paris and an agent-based simulation protocol testing various hypotheses on the motives that drive agent behaviors. A previous work (Rouchier et al. 2007) had already modeled the dynamics of advice-seeking among judges and studied the implications of different rationality assumptions on the shape of the emerging network. Here, we add an influence model to the previously examined advice-seeking relationships in order to explore the possibility that there is a form of “culture” at the Court that harmonizes the opinions of members over time; we identify a set of relevant stylized facts, and we use new indicators to evaluate how agents choose with whom to interact within this framework. The basic assumptions we analyze are that they seek advice from senior judges who are higher up in the hierarchy, who enjoy high reputation, or who are similar to them. Our simulations test which criterion –or which combination of criteria– is most credible, by comparing both the properties of the emerging network and the dynamics of opinion at the Court to the stylized facts. Our results single out the combination of criteria that most likely guide individuals' selection of advisors and provide insight into their effects on opinion formation.Advice network ; Agent-Based Simulation ; Influence Model ; Opinion Dynamics ; Hierarchy ; Reputation

    Time vs. Information Tradeoffs for Leader Election in Anonymous Trees

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    The leader election task calls for all nodes of a network to agree on a single node. If the nodes of the network are anonymous, the task of leader election is formulated as follows: every node vv of the network must output a simple path, coded as a sequence of port numbers, such that all these paths end at a common node, the leader. In this paper, we study deterministic leader election in anonymous trees. Our aim is to establish tradeoffs between the allocated time τ\tau and the amount of information that has to be given a priori\textit{a priori} to the nodes to enable leader election in time τ\tau in all trees for which leader election in this time is at all possible. Following the framework of algorithms with advice\textit{algorithms with advice}, this information (a single binary string) is provided to all nodes at the start by an oracle knowing the entire tree. The length of this string is called the size of advice\textit{size of advice}. For an allocated time τ\tau, we give upper and lower bounds on the minimum size of advice sufficient to perform leader election in time τ\tau. We consider nn-node trees of diameter diamDdiam \leq D. While leader election in time diamdiam can be performed without any advice, for time diam1diam-1 we give tight upper and lower bounds of Θ(logD)\Theta (\log D). For time diam2diam-2 we give tight upper and lower bounds of Θ(logD)\Theta (\log D) for even values of diamdiam, and tight upper and lower bounds of Θ(logn)\Theta (\log n) for odd values of diamdiam. For the time interval [βdiam,diam3][\beta \cdot diam, diam-3] for constant β>1/2\beta >1/2, we prove an upper bound of O(nlognD)O(\frac{n\log n}{D}) and a lower bound of Ω(nD)\Omega(\frac{n}{D}), the latter being valid whenever diamdiam is odd or when the time is at most diam4diam-4. Finally, for time αdiam\alpha \cdot diam for any constant α<1/2\alpha <1/2 (except for the case of very small diameters), we give tight upper and lower bounds of Θ(n)\Theta (n)
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