In his seminal work, Valiant defined algebraic analogs for the classes P and NP, which are known today as VP and VNP. He also showed that the permanent is VNP-complete (that is, the permanent is in VNP and any problem in VNP is reducible to it). We will describe the ideas behind the proof of this completeness of the permanent.
School of Mathematics
We prove that every graph has a spectral sparsifier with a number of edges linear in its
number of vertices. As linear-sized spectral sparsifiers of complete graphs are expanders, our
sparsifiers of arbitrary graphs can be viewed as generalizations of expander graphs.
In particular, we prove that for every d > 1 and every undirected, weighted graph G =
(V,E,w) on n vertices, there exists a weighted graph H = (V, F, ~w) with at most dn edges
such that for every x ∈ ℜV ,
For the past decade, the Institute’s Science Initiative Group (SIG) has worked with the World Bank and other partners to strengthen science in developing nations. In this talk, Phillip Griffiths, who helped create SIG when he was Director of the Institute from 1991 to 2003, will address the context for and evolution of SIG’s programs, with emphasis on the new Carnegie–IAS Regional Initiative in Science and Education (RISE), which prepares Ph.D.-level scientists and engineers in sub-Saharan Africa through university-based research and training networks.
Although the concept of randomness is ubiquitous, it turns out to be difficult to generate a truly random sequence of events. The need for “pseudorandomness” in various parts of modern science, ranging from numerical simulation to cryptography, has challenged our limited understanding of this issue and our mathematical resources. In this talk, Professor Jean Bourgain explores some of the problems of pseudorandomness and tools to address them.