Workshop: an Overdue Overhaul for Network Theory Their Way

January / February 2016 UPDATE IN THIS ISSUE > Designing difficult problems 2 > Anomalous economics 2 > Online health data 3 > School for sustainability 3 > First complexity school in India 3 > Science of city skylines 3 > Two new SFI trustees 4 > Artist Joerael Elliott 4 > Upcoming SFI events 4 RESEARCH NEWS Mapping the movements of birds and beasts Be they creatures of land, sea, or air, most animal species migrate. Whales, salmon, songbirds, and butterflies, for example, all travel thousands of kilome- ters to and from breeding and feeding Partial map of the Internet. Nodes represent IP addresses. Edge (line) lengths indicate delay duration between two nodes. Node colors: dark blue .net, .ca, .us; green grounds every year. .com, .org; red .mil, .gov, .edu; yellow .jp, .cn, .tw, .au, .de; magenta .uk, .it, .pl, .fr; gold .br, .kr, .nl; white unknown. (Image: Matt Britt, Wikimedia Commons) Theory and lab experiments suggest mi- grating en masse can help animals find Workshop: An overdue overhaul for network theory their way. Creatures traveling together are thought to pool the many direction- Networks are everywhere – from social are too simple,” says Moore, who dwells at SFI workshop, Inference on Networks: al estimates of the members of a group, interactions to species feeding relationships the intersection of physics, mathematics, and Algorithms, Phase Transitions, New Models, in essence tapping into the “wisdom of to the algorithms that pull information from computer science. “They don’t capture the and New Data. Moore co-organized the the crowd.” large datasets. Because of its broad utility in rich structure of real networks like power meeting with computer scientist Aaron So goes the hypothesis, anyway. Testing quantifying interacting systems, network grids or food webs.” Clauset (University of Colorado Boulder) and it is not easy. The challenge of actually theory now finds application in many physicist Mark Newman (University of Networks should be approached not as static tracing the individual trajectories of disciplines. But network science, like any Michigan), both SFI external professors. emerging field, needs to keep up with the objects, but as dynamic systems that change group-traveling animals in the wild has times. in time, he says. Similarly, nodes and edges The workshop’s second goal, Moore says, kept the available data sparse. aren’t flat and anonymous – they often have was to assemble researchers from disparate “Technology is about to change this,” A network is traditionally regarded as a static rich metadata, like location for nodes or fields to forge novel insights. The last array of nodes connected by links, but an duration for edges, that should be incorpo- explains SFI Omidyar Fellow Andrew decade, he says, brought an “exciting flow overhaul of that view is long overdue, says rated into new models. Berdahl. He has been awarded a Na- of ideas” among physicists, mathematicians, SFI Professor Cristopher Moore. tional Science Foundation grant to use and computer scientists who create algo- Moving beyond the antiquated view of airborne drones to study a caribou herd “Many of the models we’ve had in the past networks was one goal of a mid-December > more on page 4 as it travels from its summer territory on Victoria Island above the Arctic Circle to its winter grounds on main- RESEARCH NEWS land Canada. The Dolphin-Union herd, a migratory Semantically speaking: Does meaning structure unite languages? population of barren-ground caribou in northern Canada, “is an excellent We create words to label people, places, semantic nearness between concepts,” linguistic history qualitatively. (He and test case for collective navigation be- actions, thoughts, and more so we can says co-author and SFI Professor Tanmoy collaborators had previously developed cause they face a unique navigational express ourselves meaningfully to others. Bhattacharya. “For example, are the this quantitative method to study changes challenge annually as they traverse Do our shared cognitive abilities and de- concepts of sun and moon close to each in sounds of words as languages evolve.) treacherous ice bridges,” says Berdahl, pendence on languages naturally provide other, as they are both bright blobs in the referring to autumn, when the herd a universal means of organizing certain sky? How about sand and sea, as they “Translation uncovers a disagreement congregates on shore and ventures concepts? Or do environment and culture occur close by? Which of these pairs is the between two languages on how concepts out on newly frozen ice to cross the influence each language uniquely? closer? How do we know?” are grouped under a single word,” says co-author and SFI researcher Hyejin Youn. 30-plus-kilometer-wide Dolphin and Using a new methodology that mea- Translation, the mapping of relative word “Spanish, for example, groups ‘fire’ and Union Strait. sures how closely words’ meanings are meanings across languages, would provide ‘passion’ under ‘incendio,’ whereas “The idea is to use unmanned aerial related within and between languages, clues. But examining the problem with sci- Swahili groups ‘fire’ with ‘anger’ (but an international team of researchers has entific rigor called for an empirical means not ‘passion’).” vehicles – drones – to film animals revealed that for many universal concepts, to denote the degree of semantic related- from above, then use computer vision the world’s languages feature a common ness between concepts. To quantify the problem, the researchers software to track individuals,” he says. structure of semantic relatedness. chose a few basic concepts that we see Once he has the trajectory of each To get reliable answers, Bhattacharya in nature (sun, moon, mountain, fire, and animal in a group, he can work out in- “Before this work, little was known about needed to fully quantify a comparative so on). Each concept was translated from teraction rules between individuals and how to measure [a culture’s sense of] the method that is commonly used to infer > more on page 2 > more on page 4 SFI IN THE NEWS The Wall Street Journal on December 11, Dunne and Postdoctoral Fellow Marcus Science magazine highlighted a proposed article in the leadership publication in an interactive piece on sustainability and Hamilton on December 23. new approach to identifying cell types Strategy+Business that recounts the histo- urbanization, highlighted SFI’s finding that based on gene expression patterns that ry of this research, beginning with insights human interaction and innovation seem to Articles in Quanta and Wired quote SFI reveal which parts of a cell’s genome are in the late 1990s by SFI Professor Geoffrey accelerate as a city’s population grows. Omidyar Fellow Josh Grochow in articles active, rather than on traditional methods West and collaborators that organisms and describing an algorithm that many compu- of typing a cell based on its structure, cities share some intriguing mathematical SFI’s year-long complexity series in the tational complexity theorists believe might function, or location within an organism. similarities. CS Monitor launched November 3 with be a major breakthrough in the historically The approach was the subject of a recent “Complexity: Worlds hidden in plain vexing “graph isomorphism problem.” working group at SFI. A lengthy September 15 article in sight,” by SFI President David Krakauer. Sueddeutsche Zeitung, the largest-circula- His introductory essay was followed by “A MIT Technology Review on December 14 A provocative November 27 radio inter- tion daily newspaper in Germany, covered planet of cities” by SFI Professors Luis Bet- covered a recent paper by Markus Schläpfer, view on PRI’s To the Best of Our Knowl- the August 5 event in Santa Fe featuring tencourt and Geoffrey West on November Luís Bettencourt, and colleague Joey edge with SFI President David Krakauer SFI President David Krakauer, visual artist 17, “Time for new economic models” by Lee that finds that city building shapes explores the dangers of abdicating our James Drake, passages from SFI Trustee George Mason University’s Rob Axtell can be predicted as a function of popu- free will to the almighty app. Cormac McCarthy’s forthcoming novel and SFI External Professor Doyne Farmer lation size, with potentially important The Passenger, and music by McCarthy’s on December 1, and “Are humans truly implications for carbon emissions and SFI’s cities and urbanization research son John Francis McCarthy. n unique?” by SFI VP for Science Jennifer sustainability. is featured in a lengthy November 9 Nonlinearities From the editor RESEARCH NEWS RESEARCH NEWS Art and science are colliding a lot here lately. This fall we were treated to Ice Designing difficult problems Anomalous Station Quellette, an exhibition of digital collages by Santa Fe artist Lauren The traveling salesman problem is easy to de- A common approach to difficult optimization economists to Oliver. ISQ tells the story of a “tiny scribe and hard to solve with certainty. It goes problems is a reverse-engineering process outpost on a doomed planet,” narrated like this: A salesman – or a UPS driver, or the called “planting solutions,” in which re- convene at SFI from the distant future but set in the Tooth Fairy – must visit a number of cities and searchers start with a dataset and devise a past, present, and near-future Arctic end where she or he began. What’s the most problem that describes the data. Circle. From the perspective of artificial Last year, at Her Majesty’s Treasury in efficient route? With more cities, the problem hindsight, the warning signs of plan- “Imagine you measured some experimental London, a global team of economists becomes vastly more complex. etary change are, well, glaring. A beauti- result, and you know it could be under- calling themselves Curriculum Open- ful, moving work. More at http://isq.io. access Resources for Economics, or CORE, Computer scientists study optimization prob- stood with a mathematical model,” says launched an ambitious, unconventional In November, we hosted a unique lems like the traveling salesman not because SFI External Professor Helmut Katzgraber project.

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