Dr. Johannes Hoffmann

Dr. Johannes Hoffmann
Saarland University
Department of Mathematics
D-66123 Saarbruecken

room 224 (building E 2 4)
phone: +49-681-302-4515
mail: johannes.hoffmann[at]math.uni-sb.de
office hours: by prior arrangement




Research interests

  • Ore localization (esp. in G-algebras): theoretical results, algorithms, and implementation.
  • Non-commutative rational functions: linearization, minimization, and applications.


See also: arXiv.org


Jul 2021ISSAC 2021, Saint Petersburg, Russia (virtual)
Sep 2020CASC 2020, Linz, Austria (virtual)
Jul 2020ISSAC 2020, Kalamata, Greece (virtual)
May 2020Real Algebraic Geometry with a View Toward Hyperbolic Programming and Free Probability, Oberwolfach, Germany
Jul 2019IWOTA 2019, Lisbon, Portugal
Jul 2019SIAM AG 2019, Bern, Switzerland
May 2019Computeralgebra-Tagung 2019, Kassel, Germany
Jul 2018ISSAC 2018, New York, USA
Jul 2017ISSAC 2017, Kaiserslautern, Germany
May 2017Computeralgebra-Tagung 2017, Kassel, Germany
Mar 2017FELIM 2017, Limoges, France
Aug 2016ACA 2016, Kassel, Germany
Sep 2015CASC 2015, Aachen, Germany



I am the author of the following libraries for the computer algebra system SINGULAR, which are included in the distribution:

olga.libConstructive computations in Ore-localized G-algebras.
ncloc.libNew data type ncloc for Ore localizations, to be used with olga.lib.
ncfrac.libNew data type ncfrac for non-commutative fractions in Ore localizations, to be used with olga.lib and ncloc.lib.


I am the author of the following libraries for the Julia language:

NCDist.jlNCDist.jl is a Julia package to compute distributions as well as Brown measures of (self-adjoint) rational expressions and matrix-valued elements given the distributions of the variables. (joint work with Tobias Mai)