syslog
21Oct/110

NetMob 2011

Posted by Salvatore Scellato

Last week I was in (the other) Cambridge, attending the "Second conference on the Analysis of Mobile Phone Datasets and Networks", or NetMob, held at the MIT Media Lab together with SocialCom 2011. NetMob provides an interesting format: there is only one track of short contributed talks, with the possibility to present recent results or results submitted elsewhere.  Speakers have about 10-12 minutes to present their work and then there is plenty of time to discuss ideas network with other people over 2 days. I gave two talks: one of our research on the effect of geographic distance on online social networks and another on our recent work on universal patterns in urban human mobility.

The unifying theme of the workshop is the analysis of mobile phone datasets: as people user mobile devices more and to do more things, these datasets help us to understand complex processes such as spread of information, human mobility, the usage of urban geography and so on. Indeed, the range of talks presented at the workshop was impressive and fascinating, spanning between two main points: the first day focused more on studying user mobility, while the second day featured works on social behaviour.

Among the most innovative works during the first day there was a talk by people at MIT & Berkeley on using mobile phone CDRs to make sense of urban roads, proposing to use a the Gini coefficient to measure the diversity of individual traffic carried by each street. Individual user mobility was the main theme of several talks: I particularly liked one on the seasonal patterns of user movements, presented by Northeastern University researchers, and one by a large team led by Vincent Blondel on exploring the spatio-temporal properties of human mobility and the regular home-work routine of many users. Laszlo Barabasi gave an invited talk on mobility and predictability, presenting much of his last work and trying to connect the statistical properties of human mobility to the performance limits of many related applications that rely on user regularity. Finally, AT&T Labs presented their results on why it is impossible to anonymize location data.

The second day featured works on the social properties of mobile phone communication between users. Researchers at CMU presented their results on quantifying how social influence might compel users to adopt some products by using randomization techniques. Another interesting talk by a a joint team UC3M and Telefonica presented how time allocation in social networks has strong constraint that are likely to affect and be affect by the social structure itself: well-connected hubs have a lower importance on information transmission than less connected users, with important consequences on many dynamic social processes. Sandy Pentland have another invited talk, offering a wide overview of how mobile devices are changing the technological landscape with their ubiquitous sensing capabilities. Another interesting talk discussed the economic value of mobile location data, presenting scenarios user actions can be monetized and profit shared among different service providers.

Overall NetMob provided an insightful venue for discussions and potential collaborations, always revolving around the idea that as mobile devices become more and more ubiquitous they will offer new fascinating research opportunities.

Many more details about all the talks in the book of abstracts.

 

15Jul/110

Socio-spatial properties of online social networks

Posted by Salvatore Scellato

Some social scientists have suggested that the advent of fast long-distance travel and cheap online communication tools might have caused the "death of distance": as described by Frances Cairncross, the world appears shrinking as individuals connect and interact with each other regardless of the geographic distances which separates them. Unfortunately, the lack of reliable geographic data about large-scale social networks has hampered research on this specific problem.

However, the recent growing popularity of location-based services such as Foursquare and Gowalla has unlocked large-scale access to where people live and who their friends are, making possible to understand how distance and friendship ties relate to each other.

In a recent paper which will appear at the upcoming ICWSM 2011 conference we study the socio-spatial properties arising between users of three large-scale online location-based social networks. We discuss how distance still matters: individuals tend to create social ties with people living nearby much more likely than with persons further away, even though strong heterogeneities still appear across different users.

30May/110

Place-Friends: designing a link prediction system for location-based services

Posted by Salvatore Scellato

Online social networks often deploy friend recommending systems, so that new users can be discovered and new social connections can be created. Since these service have easily millions of users, recommending friends potentially involves searching a huge prediction space: this is why platforms such as Facebook, LinkedIn and Twitter merely focus their prediction efforts on friends-of-friends, that is, on users that are only 2 hops away in the social network, sharing at least a common friend. Extending prediction efforts beyond this social circle is simply not worth it.

017/365 areyoucheckedin?

Nonetheless, in location-based social networks there is an unprecedented source of potential promising candidates for recommending new friends: the places where user check-in at.  In a recent paper which will appear at the upcoming ACM SIGKDD 2011 conference we address the problem of designing a link prediction system which exploits the properties of the places that users visit.

4Apr/110

20th International World Wide Web Conference – WWW 2011

Posted by Salvatore Scellato

I am just back from Hyderabad, in India, where I attended the 20th International World Wide Web Conference, also known as WWW 2011, to present our work on tracking geographic social cascades to improve video delivery.  This conference, organised as usual by the International World Wide Web Conference Committee (IW3C2),  represents the annual opportunity for the international community to discuss and debate the evolution of the Web, providing a mixture of academic and industrial content.

The word cloud shows pretty well the main themes of the conference this year, which heavily revolved around two large pivotal aspects: "social" and "search". Interestingly, there was not any attempt of merging the two things together, as Aardvark tried last year. Not surprisingly, "networks" are still popular in the community, and "Twitter" still enjoys a lot of interest, even though this may change with their new controversial Terms Of Service, which are likely to hamper social media data harvesting.

Overall it is a fairly big conference, with 2 initial days of workshops, tutorial and panels and then 3 days with 81 research papers. Also, there were three world-known personalities such as Dr. Abdul Kalam, Sir Tim Berners-Lee and Christos Papadimitriou that gave a keynote each. I will give a brief summary of the main research themes, with pointers to the most interesting papers. However, it was physically impossible to attend all the research sessions, as they were often happening simultaneously: you can find much more information on the conference website and on the official proceedings.

28Mar/110

Tracking shared YouTube links might help improve video delivery performance

Posted by Salvatore Scellato

Even though sharing YouTube links with our friends on Twitter and Facebook might seem a simple and quick action with no consequences, when millions of users are doing so every day it is something much more important. In fact, it becomes possible to track how interest for content items is spreading across social networks to improve performance of the content delivery networks serving those items. This is the problem we have addressed in a recent paper which will appear at the upcoming WWW 2011 conference.