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Fachgebiet Algorithmische AlgebraMahmut Levent Doğan

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Wissenschaftliche Mitarbeiter

Mahmut Levent Doğan

Anschrift
Technische Universität Berlin
Institut für Mathematik
Sekretariat MA 3-2
Straße des 17. Juni 136
10623 Berlin
 
Büro
Raum MA 303 (3. OG)
Institut für Mathematik

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Sekretariat
Beate Nießen
Raum MA 318
Tel.: +49 (0)30 314 - 25771

eMail
dogan@math.tu-berlin.de 

Telefon
+49 (0)30 314-73989
Faxgerät
+49 (0)30 314 - 25839
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Publikationen in der Arbeitsgruppe

Polynomial time algorithms in invariant theory for torus actions
Citation key BDMWW-Polynomial-time-algorithms-in-invariant-theory-for-torus-actions
Author Peter Bürgisser and M. Levent Doğan and Visu Makam and Michael Walter and Avi Wigderson
Year 2021
Month 02
Abstract An action of a group on a vector space partitions the latter into a set of orbits. We consider three natural and useful algorithmic "isomorphism" or "classification" problems, namely, orbit equality, orbit closure intersection, and orbit closure containment. These capture and relate to a variety of problems within mathematics, physics and computer science, optimization and statistics. These orbit problems extend the more basic null cone problem, whose algorithmic complexity has seen significant progress in recent years. In this paper, we initiate a study of these problems by focusing on the actions of commutative groups (namely, tori). We explain how this setting is motivated from questions in algebraic complexity, and is still rich enough to capture interesting combinatorial algorithmic problems. While the structural theory of commutative actions is well understood, no general efficient algorithms were known for the aforementioned problems. Our main results are polynomial time algorithms for all three problems. We also show how to efficiently find separating invariants for orbits, and how to compute systems of generating rational invariants for these actions (in contrast, for polynomial invariants the latter is known to be hard). Our techniques are based on a combination of fundamental results in invariant theory, linear programming, and algorithmic lattice theory.
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