Christoph Koutschan

ORCID: 0000-0003-1135-3082
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Research Areas
  • Advanced Combinatorial Mathematics
  • Advanced Mathematical Identities
  • Polynomial and algebraic computation
  • Mathematics and Applications
  • Algebraic structures and combinatorial models
  • Mathematical functions and polynomials
  • Advanced Numerical Analysis Techniques
  • Nonlinear Waves and Solitons
  • Algebraic Geometry and Number Theory
  • Advanced Topics in Algebra
  • Geometric and Algebraic Topology
  • Advanced Algebra and Geometry
  • Commutative Algebra and Its Applications
  • Algorithms and Data Compression
  • Coding theory and cryptography
  • graph theory and CDMA systems
  • Numerical methods for differential equations
  • Advanced Graph Theory Research
  • Mathematical Dynamics and Fractals
  • Computational Geometry and Mesh Generation
  • Analytic Number Theory Research
  • Advanced Differential Equations and Dynamical Systems
  • Advanced Materials and Mechanics
  • Numerical Methods and Algorithms
  • History and Theory of Mathematics

Johann Radon Institute for Computational and Applied Mathematics
2015-2024

Austrian Academy of Sciences
2015-2024

Johannes Kepler University of Linz
2007-2021

Inria Saclay - Île de France
2012

Institut national de recherche en informatique et en automatique
2012

Association for Symbolic Logic
2010-2012

Tulane University
2010-2011

RISC Software (Austria)
2008

The holonomic systems approach was proposed in the early 1990s by Doron Zeilberger. It laid a foundation for algorithmic treatment of function identities. Frédéric Chyzak later extended this framework introducing closely related notion ∂-finite functions and placing their manipulation on solid grounds. For practical purposes it is convenient to take advantage both concepts which not too much restriction: class that are contains many elementary (such as rational functions, algebraic...

10.1145/1823931.1823954 article EN ACM communications in computer algebra 2010-06-24

10.1007/s11786-010-0055-0 article EN Mathematics in Computer Science 2010-09-01

We present a computer-aided, yet fully rigorous, proof of Ira Gessel's tantalizingly simply-stated conjecture that the number ways walking $2n$ steps in region $x+y \geq 0, y 0$ square-lattice with unit east, west, north, and south directions, start end at origin, equals $16^n\frac{(5/6)_n(1/2)_n}{(5/3)_n(2)_n}$ .

10.1073/pnas.0901678106 article EN Proceedings of the National Academy of Sciences 2009-06-26

Elaborating on an approach recently proposed by Mark van Hoeij, we continue to investigate why creative telescoping occasionally fails find the minimal-order annihilating operator of a given definite sum or integral. We offer explanation based consideration residues.

10.48550/arxiv.2502.03757 preprint EN arXiv (Cornell University) 2025-02-05

We propose a version of the classical shape lemma for zero-dimensional ideals commutative multivariate polynomial ring to noncommutative setting in an algebra differential operators.

10.48550/arxiv.2502.11787 preprint EN arXiv (Cornell University) 2025-02-17

10.1016/j.disc.2025.114501 article EN Discrete Mathematics 2025-03-27

Designing mechanical devices, called linkages, that draw a given plane curve has been topic interested engineers and mathematicians for hundreds of years, recently also computer scientists. Already in 1876, Kempe proposed procedure solving the problem full generality, but his constructions tend to be extremely complicated. We provide novel algorithm produces much simpler works only parametric curves. Our approach is transform into factorization task over some noncommutative algebra. show how...

10.1090/mcom/3120 article EN Mathematics of Computation 2016-03-23

For multiple-input-multiple-output (MIMO) spatial-multiplexing transmission, zero-forcing (ZF) detection is appealing because of its low complexity. Our recent MIMO ZF performance analysis for Rician-Rayleigh fading, which relevant in heterogeneous networks, has yielded the outage probability and ergodic capacity infinite-series expressions. Because they arose from expanding confluent hypergeometric function <sub xmlns:mml="http://www.w3.org/1998/Math/MathML"...

10.1109/twc.2014.2385075 article EN IEEE Transactions on Wireless Communications 2014-12-22

Continuing a series of articles in the past few years on creative telescoping using reductions, we develop new algorithm to construct minimal telescopers for algebraic functions. This is based Trager's Hermite reduction and polynomial reduction, which was originally designed hyperexponential functions extended case this paper.

10.1145/2930889.2930901 preprint EN 2016-07-19

The conjecture that the orbit-counting generating function for totally symmetric plane partitions can be written as an explicit product formula, has been stated independently by George Andrews and David Robbins around 1983. We present a proof of this long-standing conjecture.

10.1073/pnas.1019186108 article EN Proceedings of the National Academy of Sciences 2011-01-24

Our goal is to compute the minimal-order recurrence of colored Jones polynomial 7_4 knot, as well for first four double twist knots. As a corollary, we verify AJ Conjecture simplest knot with reducible non-abelian SL(2,C) character variety. To achieve our goal, use symbolic summation techniques Zeilberger's holonomic systems approach and an irreducibility criterion q-difference operators. For latter improved version qHyper algorithm Abramov-Paule-Petkovsek show that given operator has no...

10.2140/agt.2013.13.3261 article EN Algebraic & Geometric Topology 2013-10-10

10.1016/j.jsc.2017.07.005 article EN publisher-specific-oa Journal of Symbolic Computation 2017-07-14

We study the face-centered cubic (fcc) lattice in up to six dimensions. In particular, we are concerned with Green functions (LGFs) and return probabilities. Computer algebra techniques, such as method of creative telescoping, used for deriving an ODE a given LGF. For four- five-dimensional fcc lattices, give rigorous proofs ODEs that were conjectured by Guttmann Broadhurst. Additionally, find LGF six-dimensional lattice, result was not believed be achievable current computer hardware.

10.1088/1751-8113/46/12/125005 article EN Journal of Physics A Mathematical and Theoretical 2013-03-06

Laman graphs model planar frameworks that are rigid for a general choice of distances between the vertices. There finitely many ways, up to isometries, realize graph in plane. Such realizations can be seen as solutions systems quadratic equations prescribing pairs points. Using ideas from algebraic and tropical geometry, we provide recursive formula number complex such systems.

10.1137/17m1118312 article EN SIAM Journal on Applied Algebra and Geometry 2018-01-01

The Apagodu-Zeilberger algorithm can be used for computing annihilating operators definite sums over hypergeometric terms, or integrals hyperexponential functions. In this paper, we propose a generalization of which is applicable to arbitrary $\partial$-finite analogy the case, introduce notion proper We show that always succeeds these functions, and give tight priori bound order output operator.

10.1145/2608628.2608641 preprint EN 2014-07-01

We study q-holonomic sequences that arise as the colored Jones polynomial of knots in 3-space. The minimal-order recurrence for such a sequence is called (non-commutative) A-polynomial knot. Using "method guessing", we obtain this explicitly K_p = (-2, 3, 3+2p) pretzel p -5, ..., 5. This particularly interesting family since pairs (K_p, -K_{-p}) are geometrically similar (in particular, scissors congruent) with character varieties. Our computation non-commutative (a) complements done by...

10.1080/10586458.2012.651409 article EN Experimental Mathematics 2012-09-01

We propose a differential analog of the notion integral closure algebraic function fields. present an algorithm for computing algebra defined by linear operator. Our is direct van Hoeij's bases

10.1145/2755996.2756658 preprint EN 2015-06-24

Computing the number of realizations a minimally rigid graph is notoriously difficult problem. Toward this goal, for graphs that are in plane, we take advantage recently published algorithm, which fastest available method, although its complexity still exponential. Combining computational results with theory constructing new by gluing, give lower bound on maximal possible (complex) given vertices. We extend these ideas to three dimensions and derive similar bounds, exploiting data from...

10.1080/10586458.2018.1437851 article EN cc-by Experimental Mathematics 2018-03-27

10.1016/j.jsc.2018.06.003 article EN publisher-specific-oa Journal of Symbolic Computation 2018-06-15

We prove an integrability criterion of order 3 for a homogeneous potential degree -1 in the plane. Still, this depends on some integer and it is impossible to apply directly except families potentials whose eigenvalues are bounded. To address issue, we use holonomic asymptotic computations with error control form V(r,\theta)=r^{-1} h(\exp(i\theta)) h polynomial less than 3. find then all meromorphically integrable form.

10.1063/1.4746691 article EN Journal of Mathematical Physics 2012-08-01
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