While much conventional sociological research assesses statistical relationships among variables, my research has focused on elucidating social processes underlying those relationships. I have done so by developing formal theoretical models and methods of longitudinal data collection and analysis, as well as applying these theories and methods in research that investigates generative dynamics r...

Complex systems share a unique and fascinating property: they exhibit emergence, a process that, over time, gives rise to novel structures (e.g. behaviors, features) that are produced by but irreducible to the low-level mechanisms that govern the system (Holland, 1988, 2000). The complexity paradigm proposes that understanding emergent properties requires a shift in focus, from the unique chara...

2007– W5, or A World Wide Web Without Walls. Conceived of and now prototyping W5, a new architecture for the web. The Facebooks and OpenSocials of the world represent new architectures for application development. W5 argues that they insufficiently protect users and unnecessarily encumber application developers. W5 proposes an alternative architecture, under which users retain control of their ...

Whose interests should count and how should various interests be balanced at the pediatric patient's bedside? The interests of the child patient clearly count. Recently, however, many authors have argued that the family's interests also count. But how should we think about the interests of others? What does it mean to talk about "the family" in this context? Does it really just mean the interes...

Since the early 2000s, power has been the central problem that limits the performance of computer systems, from datacenters to smartphones and wearable devices. Data movement is the primary contributor to power dissipation in nanometer ICs. Consider, for instance, the energy cost of performing a double precision addition on a graphics processing unit (GPU) implemented at the 22nm technology nod...

My research seeks to explain how we learn about and represent the world. I empirically examine how people learn word-object mappings (i.e., nouns) from a series of situations comprised of multiple words and objects, as an infant or a traveler may do. Using mathematical models of memory and associative learning, I seek to discover the mechanisms underlying human word-learning behavior. I also in...

Over the past few years 1, I have been studying the representation of time, as it appears in knowledge-based and classical planning. My goals have been to understand (i) the way future actions can be planned both with and without domain knowledge and (ii) how artificial agents and human beings can organize the future and react to the present. My previous work has focused on using engineering kn...

My research interests lie in the areas of enumerative and algebraic combinatorics. In particular, I am studying pattern avoidance for affine permutations and its applications. For many years, many mathematicians have studied pattern avoidance in permutations. Sometimes the questions are as simple as, ”How many permutations avoid a given set of patterns?” For example, the number of permutations ...