Institut für Numerische und Angewandte Mathematik
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Lotzestr. 16-18

Institute for Numerical and
Applied Mathematics
University of Goettingen
Lotzestr. 16-18
D-37083 Goettingen, Germany

Approach

Office
Ground Floor, Room 8
Tel.: +49 551 39 4502
Fax: +49 551 39 33944
EMail


Library
Second Floor, Room 209
Tel. +49 551 39 4512



Projects



Special Teaching Projects



News



Service

News


Colloquium on Applied Mathematics

April, 11th, 2017, 5.15 p.m.

Prof. Silvia Bonettini,
University of Ferrara

Title:
From gradient projection to forward-backward methods for variational inverse problems more...



Lecture series

Prof. Thomas McCormick, UBC Sauer, Vancouver (http://www.sauder.ubc.ca/Faculty/People/Faculty_Members/McCormick_Thomas) will be here from March 20-22, 2017.

He will give a lecture series on the subject "Combinatorial algorithms for submodular function minimization".

Abstract:
Submodular functions arise in a wide variety of applications, such as linear algebra, matroids, network flows, machine learning, natural language processing, etc. A key subroutine in many of these applications is to minimize a given submodular function. This course will introduce submodular functions, along with enough algorithmic tools to describe a variant of Schrijver's Algorithm, one of the breakthrough combinatorial algorithms for minimizing submodular functions.

Here are the dates for the lecture series:
Mon, 20 March 2017: 10:15-11:45, NAM-SR (MN55)
Tue, 21 March 2017: 10:15-11:45, NAM-SR (MN55)
Wed, 22 March 2017: 10:15-11:45, NAM-SR (MN55)


He will further give a talk in our colloquium on the subject "Computing closest vectors in zonotopal lattices".

Abstract:
A lattice L is the set of vectors arising from integer linear combinations of given basis vectors in R^n. Given some vector x, the Closest Vector Problem (CVP) is to find a vector v in L of minimum l_2-norm distance to x. CVP is a fundamental problem for lattices with many applications, and it is in general NP Hard.
A zonotopal lattice is given as the set of integer points {v | Mv = 0} when M is a totally unimodular matrix. We show how to adapt the Cancel and Tighten algorithm of Karzanov and McCormick to solve CVP for zonotopal lattices in O(n^3) time via the Seymour decomposition of totally unimodular matrices. The algorithm uses the decomposition to reduce the problem to a series of subproblems that are piecewise linear convex circulation and co-circulation network flow problems.

The talk will take place on Tuesday, March 21, 17:15 in the NAM seminar room (MN55).



Workshop on the occasion of the 75th birthday of Rainer Kress

Göttingen, May 5, 2017 more...