Publications
107 results found
Clough JR, Evans TS, 2015, Time & Citation Networks, 15th International Conference of the International-Society-for-Scientometrics-and-Informetrics (ISSI) on Scientometrics and Informetrics, Publisher: INT SOC SCIENTOMETRICS & INFORMETRICS-ISSI, Pages: 1073-1078, ISSN: 2175-1935
Evans T, Lambiotte R, 2014, LineGraphCreator
This is code to implement our weighted line graphs, i.e. graphs whose nodes are the edges of the original graph which aslo capture the correct dynamical features of the original network. Weighted line graphs provide an alternative, valuable representation of the system's topology, and have important applications in community detection. The usual node partition of a line graph naturally leads to an edge partition of the original graph. This identification allows us to use traditional partitioning methods in order to address the long-standing problem of the detection of overlapping communities.Here we provide our simple C++ line graph code which takes in a graph as an edge list and outputs different types of line graph as another edge list. An executable suitable for most Windows machines is included as is basic documentation. This code been used successfully on a graph which produced 5.5e8 stubs in its line graph, though a special machine was used for this as it needs more than 4Gb of RAM memory. On a 4Gb machine a line graph with 4.5e7 stubs was created.We also have java based code which is part of a much bigger package.Discussions, papers and slides from talks:-Paper: Line Graphs, Link Partitions and Overlapping Communities, Phys.Rev.E 80 (2009) 016105 [arXiv:0903.2181].Conference Paper: Overlapping Communities, Link Partitions and Line Graphs, a very slightly altered version forECCS09.Slides from talk What am I? Finding Communities in Networks Using Line Graphs given at University of Warwick Complexity Forum, 28thOctober 2009.Slides from talk Overlapping Communities, Edge Partitions and Line Graphs given at ECCS09 (University of Warwick, 22nd September 2009).Paper: Edge Partitions and Overlapping Communities in Complex Networks, Eur. Phys. J. B 2010, 77, 265–272 [arXiv:0912.4389]. This covers in more detail the case where one is interested in the different line graphs of a weighted graph.Input used for the Les Miserable network and the correpsonding outputs
Evans T, 2014, The Connected Past London 2014
A collection of material associated with The Connected Past London 2014, a one and a half day multi-disciplinary meeting held at Imperial College on the 8th and 9th of September, 2014 and attended by nearly fifty researchers. It aims to explore how concepts and techniques from network- and complexity science can be used to study archaeological and historical data. It is part of a series of meetings organised by The Connected Past team.Slides from most (but not all) talks are provided. Most talks were also recorded but the videos are yet to be made available.
Evans TS, Rivers RJ, Rivers RJ, et al., 2014, New approaches to Archaic Greek Settlement Structure, Les Nouvelles de l'archéologie, Vol: 135, Pages: 21-27, ISSN: 0242-7702
Recent developments in network theory have led to the creation of new Spatial Interaction Models (SIMs) and a reappraisal of existing models. Although not directed at the archaeology community, these models generalise the familiar gravitational models and Proximal Point Analysis (PPA) used by archaeologists for many years to help explain the archaeological record. However, a problem arises in archaeology that, with the increasing suite of plausible models that now exist, it is unclear how to choose one model over another. This can lead to the criticism that, if we hunt hard enough, we may be doing no more than finding a model which can be manipulated to conform to our preconceptions. In recent articles we have begun to address this criticism (Evans 2014, in press) with particular reference to the maritime networks of the MBA Aegean (Rivers 2014, in press). Different historical periods require different approaches and in this paper we continue this analysis by re-examining the onset of centralisation in mainland Greek city states of the 9th and 8th centuries BCE. Pioneering work on this archaic settlement structure was performed in 1987 by Rihll and Wilson (Rihll & Wilson 1987, 2: 5-32; 1991: 59-95), adapting a 'retail' model devised originally for urban planning. One alternative approach is given by a recent cost-benefit model termed ariadne, developed by ourselves (Evans, Knappett & Rivers 2009, 7: 451-79; Knappett, Evans & Rivers 2008, 82: 1009-84; 2011, 85: 1008-23), initially designed for Bronze Age maritime networks. A comparison of these models and other simpler SIMs for archaic settlements highlights the problems of modelling archaeological data. In particular we examine what constitutes model 'robustness' and the way in which different models handle 'contingency' when handling periods of rapid change.
Reiss DS, Price JJ, Evans TS, 2013, Sculplexity: Sculptures of Complexity using 3D printing, EPL, Vol: 104, ISSN: 0295-5075
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- Citations: 3
Wilting J, Evans TS, 2013, Oscillator Synchronization in Complex Networks with Non-uniform Time Delays, Complex Networks IV, Publisher: Springer, Pages: 93-100
We investigate a population of limit-cycle Kuramoto oscillators coupled in a complex network topology with coupling delays introduced by finite signal propagation speed and embedding in a ring. By numerical simulation we find that in complete graphs velocity waves arise that were not observed before and analytically not understood. In regular rings and small-world networks frequency synchronization occurs with a large variety of phase patterns. While all these patterns are nearly equally probable in regular rings, small-world topology sometimes prefers one pattern to form for a large number of initial conditions.We propose implications of this in the context of the temporal coding hypothesis for information processing in the brain and suggest future analysis to conclude the work presented here.
Rivers R, Knappett C, Evans T, 2013, Network Models and Archaeological Spaces, Computational Approaches to Archaeological Spaces, Editors: Bevan, Lake, Publisher: Left Coast Press, ISBN: 978-1-61132-346-7
Rivers R, Knappett C, Evans T, 2013, What makes a site important? Centrality, gateways and gravity, Network Analysis in Archaeology: New Approaches to Regional Interaction, Editors: Knappett, Publisher: OUP, Pages: 125-150
Evans TS, Kaube BS, Hopkins N, 2012, Temporal Evolution Of Universal Performance Indicators For Academic Publication, ECCS 2012
We show universal behaviour for two indicators of the quality of publications taken from two different data sets, papers from a single institution and those on arXiv. We demonstrate this universality for different years and subjects. This distribution is well fitted by a lognormal with a variance of around 1.3, consistent with Radicchi et al (2008). We will also discuss the evolution over time of our measures describing the data and note that simple models do not have the correct temporal behaviour for our parameters. Based on arXiv:1110.3271 with additional new material.Poster given at ECCS 2012
Evans TS, Rivers RJ, Knappett C, 2012, INTERACTIONS IN SPACE FOR ARCHAEOLOGICAL MODELS, ADVANCES IN COMPLEX SYSTEMS, Vol: 15, ISSN: 0219-5259
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- Citations: 14
Clemson T, Evans TS, 2012, The emergence of leadership in social networks, PHYSICA A-STATISTICAL MECHANICS AND ITS APPLICATIONS, Vol: 391, Pages: 1434-1444, ISSN: 0378-4371
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- Citations: 4
Evans TS, Rivers RJ, 2012, Interactions in Space for Archaeological Models, Advances in Complex Systems, Vol: 15
In this article we examine a variety of quantitative models for describingarchaeological networks, with particular emphasis on the maritime networksof the Aegean Middle Bronze Age. In particular, we discriminate betweenthose gravitational networks that are most likely (maximum entropy) andmost efficient (best cost/benefit outcomes).
Evans TS, 2012, Turnover Rate of Popularity Charts in Neutral Models
It has been shown recently that in many different cultural phenomena the turnover rate on the most popular artefacts in a population exhibit some regularities. A very simple expression for this turnover rate has been proposed by Bentley et al. 2007 and its validity in two simple models for copying and innovation is investigated in this paper. It is found that the formula in Bentley et al. is an approximation of the real behaviour of the turnover rate in the Wright-Fisher model, while it is not valid in the Moran model.
Evans TS, Hopkins N, Kaube BS, 2012, Universality of Performance Indicators based on Citation and Reference Counts, Scientometrics: an international journal for all quantitative aspects of the science of science, communication in science and science policy
We find evidence for the universality of two relative bibliometric indicatorsof the quality of individual scientific publications taken from different datasets. One of these is a new index that considers both citation and referencecounts. We demonstrate this universality for relatively well cited publicationsfrom a single institute, grouped by year of publication and by faculty or bydepartment. We show similar behaviour in publications submitted to the arXive-print archive, grouped by year of submission and by sub-archive. We also findthis distribution is well fitted by a lognormal with a variance of around 1.3which is consistent with the results of Radicchi, Fortunato, and Castellano.Our work demonstrates that comparisons can be made between publications fromdifferent disciplines and publication dates, regardless of their citation countand without expensive access to the whole world-wide citation graph. Further,it shows that averages of the logarithm of such relative bibliometric indicesdeal with the issue of long tails and avoid the need for statistics based onlengthy ranking procedures.
Evans TS, Lambiotte R, Panzarasa P, 2011, Community structure and patterns of scientific collaboration in Business and Management, SCIENTOMETRICS, Vol: 89, Pages: 381-396, ISSN: 0138-9130
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- Citations: 52
Rivers RJ, Evans TS, Knappett C, 2011, Modelling maritime interaction in the Aegean Bronze Age, II. The Theran eruption and Minoan palatial collapse, Antiquity: a quarterly review of archaeology, Vol: 85, Pages: 1008-1023
What was the effect on Late Minoan civilisation of the catastrophic destruction of Akrotiri on Thera (Santorini) by volcanic eruption? Not much, according to the evidence for continuing prosperity on Crete. But the authors mobilise their ingenious mathematical model (published in Antiquity 82: 1009–1024), this time to show that the effects of removing a major port of call could have impacted after an interval, as increased costs of transport gradually led to ever fewer routes and eventual economic collapse.
Knappett C, Rivers R, Evans T, 2011, The Theran eruption and Minoan palatial collapse: new interpretations gained from modelling the maritime network, ANTIQUITY, Vol: 85, Pages: 1008-1023, ISSN: 0003-598X
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- Citations: 60
Lambiotte R, Sinatra R, Delvenne J-C, et al., 2011, Flow graphs: Interweaving dynamics and structure, PHYSICAL REVIEW E, Vol: 84, ISSN: 1539-3755
The behavior of complex systems is determined not only by the topological organization of their interconnections but also by the dynamical processes taking place among their constituents. A faithful modeling of the dynamics is essential because different dynamical processes may be affected very differently by network topology. A full characterization of such systems thus requires a formalization that encompasses both aspects simultaneously, rather than relying only on the topological adjacency matrix. To achieve this, we introduce the concept of flow graphs, namely weighted networks where dynamical flows are embedded into the link weights. Flow graphs provide an integrated representation of the structure and dynamics of the system, which can then be analyzed with standard tools from network theory. Conversely, a structural network feature of our choice can also be used as the basis for the construction of a flow graph that will then encompass a dynamics biased by such a feature. We illustrate the ideas by focusing on the mathematical properties of generic linear processes on complex networks that can be represented as biased random walks and their dual consensus dynamics, and show how our framework improves our understanding of these processes.
Evans TS, Giometto A, 2011, Turnover Rate of Popularity Charts in Neutral Models
It has been shown recently that in many different cultural phenomena theturnover rate on the most popular artefacts in a population exhibit someregularities. A very simple expression for this turnover rate has been proposedby Bentley et al. and its validity in two simple models for copying andinnovation is investigated in this paper. It is found that Bentley's formula isan approximation of the real behaviour of the turnover rate in theWright-Fisher model, while it is not valid in the Moran model.
Expert P, Evans TS, Blondel VD, et al., 2011, Uncovering space-independent communities in spatial networks, PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, Vol: 108, Pages: 7663-7668, ISSN: 0027-8424
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- Citations: 226
Evans TS, 2010, Clique graphs and overlapping communities, JOURNAL OF STATISTICAL MECHANICS-THEORY AND EXPERIMENT, ISSN: 1742-5468
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- Citations: 122
Evans TS, Hook D, Gurney K, 2010, Collaboration Profiling in UK Higher Education, INORMS 2010 conference entitled 'Collaboration Profiling in UK Higher Education'.
Evans TS, Lambiotte R, 2009, Line Graphs of Weighted Networks for Overlapping Communities, Eur. Phys. J. B 77 (2010) 265-272
In this paper, we develop the idea to partition the edges of a weighted graphin order to uncover overlapping communities of its nodes. Our approach is basedon the construction of different types of weighted line graphs, i.e. graphswhose nodes are the links of the original graph, that encapsulate differentlythe relations between the edges. Weighted line graphs are argued to provide analternative, valuable representation of the system's topology, and are shown tohave important applications in community detection, as the usual node partitionof a line graph naturally leads to an edge partition of the original graph.This identification allows us to use traditional partitioning methods in orderto address the long-standing problem of the detection of overlappingcommunities. We apply it to the analysis of different social and geographicalnetworks.
Evans TS, Lambiotte R, 2009, Line graphs, link partitions, and overlapping communities, PHYSICAL REVIEW E, Vol: 80, ISSN: 2470-0045
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- Citations: 361
Evans TS, Lambiotte R, 2009, Overlapping Communities, Link Partitions and Line Graphs
In this paper, we use a partition of the links of a network in order to uncover its community structure. This approach allows for communities to overlap at nodes, so that nodes may be in more than one community. We do this by making a node partition of the line graph of the original network. In this way we show that any algorithm which produces a partition of nodes can be used to produce a partition of links. We discuss the role of the degree heterogeneity and propose a weighted version of the line graph in order to account for this.
Evans T, Knappett C, Rivers R, 2009, Using Statistical Physics to Understand Relational Space: A Case Study from Mediterranean Prehistory, COMPLEXITY PERSPECTIVES IN INNOVATION AND SOCIAL CHANGE, Editors: Lane, Pumain, VanderLeeuw, West, Publisher: SPRINGER, Pages: 451-479
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- Citations: 23
Evans T, 2009, Review of Dynamical Processes on Complex Networks, by A. Barrat, M. Barthélemy and A. Vespignani, Publisher: Taylor & Francis
Evans TS, Knappett C, Rivers RJ, et al., 2009, Using Statistical Physics To Understand Relational Space: A Case Study From Mediterranean Prehistory, Complexity Perspectives on Innovation and Social Change, Editors: Lane, Pumain, Leeuw, West, Lane, Pumain, Leeuw, West, Publisher: Springer Science + Business Media, Pages: 451-479, ISBN: 9781402096624
Evans TS, ADK P, You T, 2008, Are Copying and Innovation Enough?, The European Consortium for Mathematics in Industry 2008 (ECMI 2008), Publisher: Springer, Pages: 825-831
Exact analytic solutions and various numerical results for the rewiring ofbipartite networks are discussed. An interpretation in terms of copying andinnovation processes make this relevant in a wide variety of physical contexts.These include Urn models and Voter models, and our results are also relevant tosome studies of Cultural Transmission, the Minority Game and some models ofecology.
Knappett C, Evans TS, Rivers RJ, et al., 2008, Modelling Maritime Interaction In The Aegean Bronze Age, Antiquity, Vol: 82, Pages: 1009-1024
The authors raise spatial analysis to a new level of sophistication – and insight – in proposing a mathematical model of imperfect optimisation to describe maritime networks. This model encodes, metaphorically, the notion of gravitational attraction between objects in space. The space in which this interaction occurs is the southern Aegean in the Middle Bronze Age, and the objects some of the main 34 sites we know about. The gravitational potential, more sophisticated than in Newtonian physics, is interpreted as a social potential whose equilibria, sampled statistically, determine networks with settlements of particular sizes and links of particular strengths. The model can be tweaked by giving different relative importance to the cultivation of local resources or to trade, and to show what happens when a member of the network suddenly disappears.
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