## Wednesday, October 26, 2011

### Students are Awesome(ly Productive Right Now)

What's the use of a blog if you can't brag about your students?  And my students have all been doing great stuff, so I'm excited to let others know about their work. In random order...

Zhenming Liu's paper Information Dissemination via Random Walks in d-Dimensional Space will be appearing in SODA 2012.  It looks at a very natural random walk diffusion question that hadn't been solved.  Here's the arxiv version, and a slightly edited down abstract:
We study a natural information dissemination problem for multiple mobile agents in a bounded Euclidean space. Agents are placed uniformly at random in the $d$-dimensional space $\{-n, ..., n\}^d$ at time zero, and one of the agents holds a piece of information to be disseminated. All the agents then perform independent random walks over the space, and the information is transmitted from one agent to another if the two agents are sufficiently close. We wish to bound the total time before all agents receive the information (with high probability). Our work extends Pettarin et al.'s work, which solved the problem for $d \leq 2$. We present tight bounds up to polylogarithmic factors for the case $d \geq 3$.
Justin Thaler's paper on Practical Verified Computation with Streaming Interactive Proof was accepted to ITCS 2012.  I think part of its "innovation" is how well Justin puts together the theory with the implementation, showing how practical this line of work could be. Here's the arxiv version, and again a slightly edited down abstract:
When delegating computation to a service provider, as in cloud computing, we seek some reassurance that the output is correct and complete. Yet recomputing the output as a check is inefficient and expensive, and it may not even be feasible to store all the data locally. We are therefore interested in proof systems which allow a service provider to prove the correctness of its output to a streaming (sublinear space) user, who cannot store the full input or perform the full computation herself. Our approach is two-fold. First, we describe a carefully chosen instantiation of one of the most efficient general-purpose constructions for arbitrary computations (streaming or otherwise), due to Goldwasser, Kalai, and Rothblum. This requires several new insights to make the methodology more practical. Our experimental results demonstrate that a practical general-purpose protocol for verifiable computation may be significantly closer to reality than previously realized. Second, we describe techniques that achieve genuine scalability for protocols fine-tuned for specific important problems in streaming and database processing.
Finally, Giorgos Zervas's work on Daily Deals:  Prediction, Social Diffusion, and Reputational Ramifications, which I've already discussed on the blog since it got so much press play, was also just accepted to WSDM.  Giorgos is no longer my student, but working with me and Joan Feigenbaum as a postdoc, so I'll count him in the mix.