Seminars archive

With the trend of cloud computing, data and computing are moved away from desktop and are instead provided as a service from the cloud. Data-as-a-service enables access to a wealth of data across distributed and heterogeneous data sources in the cloud. It remains a challenge, however, to ensure the privacy, interoperability, and scalability for such services.\\ \\ We designed and developed DObjects, a general-purpose P2P-based query and data operations infrastructure that can be deployed in the cloud and provides access to heterogeneous data sources. The system builds on top of a distributed mediator-wrapper architecture where individual system nodes serve as mediators and/or wrappers and interact with each other in a P2P fashion what guarantees good scalability. As an analogy, the system nodes can be considered as droplets, small elements that provide similar functionality in the cloud. Just as thousands or millions of droplets form a single drop in nature, in cloud computing, groups of droplets that provide similar functionality can form a micro-cloud. Micro-clouds are an integral part of the whole cloud computing system and can provide specific services to users.\\ \\ The dissertation also discusses the novel dynamic query execution engine within the data query infrastructure that dynamically adapts to network and node (or droplet) conditions. The query processing is capable of fully benefiting from all the distributed resources to minimize the query response time and maximize system throughput. In addition to leveraging the traditional distributed query optimization techniques, the (sub)queries are deployed and executed on droplets in a dynamic and iterative manner in order to guarantee the best reaction to network and resource dynamics.\\ \\ Finally, the dissertation presents an extension to the basic DObjects model that enables access to private data that is distributed and needs anonymization. The extension enables droplets to form virtual groups in order to addresses two important privacy issues for the sensitive data: privacy of data subjects and confidentiality of data providers. The dissertation discusses decentralized protocols that enable data sharing for horizontally partitioned databases given these constraints. These protocols can be run by the groups of droplets. Concretely, given a query spanning multiple databases, the query results do not contain individually identifiable information. In addition, institutions do not reveal their databases to each other apart from the query results.

TBA

Come and attend EUMMA's first event of the year as we learn how a little mathematics can go a long way in card games, coin flipping games, and even paintball. All those with any interest in mathematics and computer science are encouraged to attend.

The Cahn-Hilliard equation constitutes a phenomenological model for phase separation in binary alloys which was proposed some 50 years ago. Initially it was thought that a complete understanding of the steady states would yield a firm understanding of the implications of the equation for phase transition. While a complete delineation of the steady states is possible at least in one dimension, a good understanding of the various stages of the dynamics such as coarsening, or the growth of the dominant length scale of the system, comes primarily via other paths.

Alongside rapid advances in algebraic geometry, algebraic topology, and K-theory, the 1970s saw the initiation of the study of quadratic forms over general algebraic varieties and the emergence of the theory of line bundle-valued quadratic forms. The theory of invariants of such forms remains quite a mystery. In this talk, I'll give an introduction to line bundle-valued forms, similarity transformations, and classical cohomological invariants of quadratic forms. I'll present a new etale cohomological invariant for line bundle-valued forms that generalizes the Clifford invariant. This invariant is related to a four-fold cover of the orthogonal similitude group.

For various (hyper)graphs F, we give sharp lower bounds on the number of copies of F in a (hyper)graph with a prescribed number of vertices and edges. Our results extend those of Rademacher, Erdos and Lovasz-Simonovits for graphs and of Bollobas, Frankl, Furedi, Keevash, Pikhurko, Simonovits and Sudakov for hypergraphs. The proofs use the hypergraph removal lemma and stability results for the corresponding Turan problem proved by the above authors.

In a corporate research environment there is always a tension between providing services to the Siemens business units, and performing short and long term research. The systems and software engineering department at SCR in Princeton performs applied research while providing both technical and management consulting services to Siemens business units and government agencies. When performing research, Siemens often partners with university colleagues from many different countries. Much of the research and work is challenging and interdisciplinary, cutting across sales, marketing, engineering and application domains.\\ \\ This talk will describe some of the challenges faced in executing very large projects, typically with a mix of hardware and software, while conducting research to improve engineering processes and support tools. Ongoing research in systems and software engineering will be described in the context of very large projects SCR has and is continuing to support, in such domains as rail transit, postal systems, integrated health care networks, automotive systems and medical products.\\ \\ Bio:\\ \\ Brian Berenbach is a senior member of the technical staff at Siemens Corporate Research in Princeton. He is an ACM Distinguished Engineer and has published extensively on software and requirements engineering. His textbook Software Systems Requirements Engineering: In Practice was recently published by McGraw-Hill. Mr. Berenbach received his M.Sc. from Emory in 1967.\\

In this talk, I will discuss an extension of Bertrand's postulate on gaps between primes to finitely generated linear group that provides an interesting variant of subgroup growth. This is also connected with the residual average of a residually finite group, a variant which quantifies residual finiteness. This talk will largely be accessible to a general audience.

A well-known conjecture by Manton Matthews and David Sumner states, that every $4$-connected $K_{1,3}$ -free graph is hamiltonian. The conjecture itself is still wide open, but several special cases have been shown so far. We will show, that if a graph is $4$-connected and $\{K_{1,3}$, $N\}$- free, where $N =$ $N(i, j, k)$, with $i + j + k = 5$ and $i$, $j$, $k \geq 0$, the graph is pancyclic.