Principal Patterns on Graphs: Discovering Coherent Structures in Datasets

Graphs are now ubiquitous in almost every field of research. Recently, new research areas devoted to the analysis of graphs and data associated to their vertices have emerged. Focusing on dynamical processes, we propose a fast, robust and scalable framework for retrieving and analyzing recurring patterns of activity on graphs. Our method relies on a novel type of multilayer graph that encodes the spreading or propagation of events between successive time steps. We demonstrate the versatility of our method by applying it on three different real-world examples. Firstly, we study how rumor spreads on a social network. Secondly, we reveal congestion patterns of pedestrians in a train station. Finally, we show how patterns of audio playlists can be used in a recommender system. In each example, relevant information previously hidden in the data is extracted in a very efficient manner, emphasizing the scalability of our method. With a parallel implementation scaling linearly with the size of the dataset, our framework easily handles millions of nodes on a single commodity server

Socially Constrained Structural Learning for Groups Detection in Crowd

Modern crowd theories agree that collective behavior is the result of the underlying interactions among small groups of individuals. In this work, we propose a novel algorithm for detecting social groups in crowds by means of a Correlation Clustering procedure on people trajectories. The affinity between crowd members is learned through an online formulation of the Structural SVM framework and a set of specifically designed features characterizing both their physical and social identity, inspired by Proxemic theory, Granger causality, DTW and Heat-maps. To adhere to sociological observations, we introduce a loss function (G-MITRE) able to deal with the complexity of evaluating group detection performances. We show our algorithm achieves state-of-the-art results when relying on both ground truth trajectories and tracklets previously extracted by available detector/tracker systems

Worker Retention, Response Quality, and Diversity in Microtask Crowdsourcing: An Experimental Investigation of the Potential for Priming Effects to Promote Project Goals

Online microtask crowdsourcing platforms act as efficient resources for delegating small units of work, gathering data, generating ideas, and more. Members of research and business communities have incorporated crowdsourcing into problem-solving processes. When human workers contribute to a crowdsourcing task, they are subject to various stimuli as a result of task design. Inter-task priming effects - through which work is nonconsciously, yet significantly, influenced by exposure to certain stimuli - have been shown to affect microtask crowdsourcing responses in a variety of ways. Instead of simply being wary of the potential for priming effects to skew results, task administrators can utilize proven priming procedures in order to promote project goals. In a series of three experiments conducted on Amazon’s Mechanical Turk, we investigated the effects of proposed priming treatments on worker retention, response quality, and response diversity. In our first two experiments, we studied the effect of initial response freedom on sustained worker participation and response quality. We expected that workers who were granted greater levels of freedom in an initial response would be stimulated to complete more work and deliver higher quality work than workers originally constrained in their initial response possibilities. We found no significant relationship between the initial response freedom granted to workers and the amount of optional work they completed. The degree of initial response freedom also did not have a significant impact on subsequent response quality. However, the influence of inter-task effects were evident based on response tendencies for different question types. We found evidence that consistency in task structure may play a stronger role in promoting response quality than proposed priming procedures. In our final experiment, we studied the influence of a group-level priming treatment on response diversity. Instead of varying task structure for different workers, we varied the degree of overlap in question content distributed to different workers in a group. We expected groups of workers that were exposed to more diverse preliminary question sets to offer greater diversity in response to a subsequent question. Although differences in response diversity were revealed, no consistent trend between question content overlap and response diversity prevailed. Nevertheless, combining consistent task structure with crowd-level priming procedures - to encourage diversity in inter-task effects across the crowd - offers an exciting path for future study

Human Computation and Convergence

Humans are the most effective integrators and producers of information, directly and through the use of information-processing inventions. As these inventions become increasingly sophisticated, the substantive role of humans in processing information will tend toward capabilities that derive from our most complex cognitive processes, e.g., abstraction, creativity, and applied world knowledge. Through the advancement of human computation - methods that leverage the respective strengths of humans and machines in distributed information-processing systems - formerly discrete processes will combine synergistically into increasingly integrated and complex information processing systems. These new, collective systems will exhibit an unprecedented degree of predictive accuracy in modeling physical and techno-social processes, and may ultimately coalesce into a single unified predictive organism, with the capacity to address societies most wicked problems and achieve planetary homeostasis.Comment: Pre-publication draft of chapter. 24 pages, 3 figures; added references to page 1 and 3, and corrected typ

Capturing Social Embeddedness: a constructivist approach

A constructivist approach is applied to characterising social embeddedness and to the design of a simulation of social agents which displays the social embedding of agents. Social embeddedness is defined as the extent to which modelling the behaviour of an agent requires the inclusion of the society of agents as a whole. Possible effects of social embedding and ways to check for it are discussed briefly. A model of co-developing agents is exhibited, which is an extension of Brian Arthur's `El Farol Bar' model, but extended to include learning based upon a GP algorithm and the introduction of communication. Some indicators of social embedding are analysed and some possible causes of social embedding are discussed

Does Targeting a Designated Area Crowd out the other Preservation Programs’ Efforts?

Maryland has introduced a number of land preservation programs over the past 40 years to permanently preserve resource lands. Although new programs can increase the number of acres being preserved, they might have unintended impact on land preservation due to interaction with existing land preservation programs. The Maryland Rural Legacy program began in 1997 by designating large contiguous blocks of land and focusing its preservation efforts only in those areas. The program’s could attract existing programs to shift their preservation effort into this designated rural legacy areas if there exist economy of scale or they subsidized existing programs’ effort through matching funds. Alternatively, it could crowd out the others’ preservation efforts in these areas if the RL program raises the cost of preserving there. Using parcel level data and a property score matching method, we find: 1) parcels in designated RL areas are more attractive to preservation programs, 2) the RL program crowds in the preservation effort of the other programs, and 3) RL program preserves more parcels and acres of land in these areas due to increased funding.Crowding effects, Designated preservation areas, Land preservation, Agricultural and Food Policy, Environmental Economics and Policy, Land Economics/Use, Resource /Energy Economics and Policy, Q18, Q24, Q28, Q58,