21 Search Results for "Kaltofen, Erich"

Document
DOI: 10.4230/LIPIcs.STACS.2011.543
Symmetric Determinantal Representation of Weakly-Skew Circuits

Authors: Bruno Grenet, Erich L. Kaltofen, Pascal Koiran, and Natacha Portier

Published in: LIPIcs, Volume 9, 28th International Symposium on Theoretical Aspects of Computer Science (STACS 2011)

Abstract
We deploy algebraic complexity theoretic techniques for constructing symmetric determinantal representations of weakly-skew circuits, which include formulas. Our representations produce matrices of much smaller dimensions than those given in the convex geometry literature when applied to polynomials having a concise representation (as a sum of monomials, or more generally as an arithmetic formula or a weakly-skew circuit). These representations are valid in any field of characteristic different from 2. In characteristic 2 we are led to an almost complete solution to a question of Buergisser on the VNP-completeness of the partial permanent. In particular, we show that the partial permanent cannot be VNP-complete in a finite field of characteristic 2 unless the polynomial hierarchy collapses.
Cite as

Bruno Grenet, Erich L. Kaltofen, Pascal Koiran, and Natacha Portier. Symmetric Determinantal Representation of Weakly-Skew Circuits. In 28th International Symposium on Theoretical Aspects of Computer Science (STACS 2011). Leibniz International Proceedings in Informatics (LIPIcs), Volume 9, pp. 543-554, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2011)

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@InProceedings{grenet_et_al:LIPIcs.STACS.2011.543,
  author =	{Grenet, Bruno and Kaltofen, Erich L. and Koiran, Pascal and Portier, Natacha},
  title =	{{Symmetric Determinantal Representation of Weakly-Skew Circuits}},
  booktitle =	{28th International Symposium on Theoretical Aspects of Computer Science (STACS 2011)},
  pages =	{543--554},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-939897-25-5},
  ISSN =	{1868-8969},
  year =	{2011},
  volume =	{9},
  editor =	{Schwentick, Thomas and D\"{u}rr, Christoph},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.STACS.2011.543},
  URN =		{urn:nbn:de:0030-drops-30426},
  doi =		{10.4230/LIPIcs.STACS.2011.543},
  annote =	{Keywords: algebraic complexity, determinant and permanent of symmetric matrices, formulas, skew circuits, Valiant’s classes}
}
Document
DOI: 10.4230/DagSemProc.09471.1
09471 Abstracts Collection – Computer-assisted proofs - tools, methods and applications

Authors: Malcolm B. Brown, Erich Kaltofen, Shin'ichi Oishi, and Siegfried M. Rump

Published in: Dagstuhl Seminar Proceedings, Volume 9471, Computer-assisted proofs - tools, methods and applications (2010)

Abstract
From 15.11. to 20.11.2009, the Dagstuhl Seminar 09471 ``Computer-assisted proofs - tools, methods and applications '' was held in Schloss Dagstuhl~--~Leibniz Center for Informatics. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available.
Cite as

Malcolm B. Brown, Erich Kaltofen, Shin'ichi Oishi, and Siegfried M. Rump. 09471 Abstracts Collection – Computer-assisted proofs - tools, methods and applications. In Computer-assisted proofs - tools, methods and applications. Dagstuhl Seminar Proceedings, Volume 9471, pp. 1-24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{brown_et_al:DagSemProc.09471.1,
  author =	{Brown, Malcolm B. and Kaltofen, Erich and Oishi, Shin'ichi and Rump, Siegfried M.},
  title =	{{09471 Abstracts Collection – Computer-assisted proofs - tools, methods and applications}},
  booktitle =	{Computer-assisted proofs - tools, methods and applications},
  pages =	{1--24},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9471},
  editor =	{B. Malcolm Brown and Erich Kaltofen and Shin'ichi Oishi and Siegfried M. Rump},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.09471.1},
  URN =		{urn:nbn:de:0030-drops-25328},
  doi =		{10.4230/DagSemProc.09471.1},
  annote =	{Keywords: Verification methods, computer algebra, computer-assisted proofs}
}
Document
DOI: 10.4230/DagSemProc.09471.2
09471 Executive Summary – Computer-assisted proofs - tools, methods and applications

Authors: Malcolm B. Brown, Erich Kaltofen, Shin'ichi Oishi, and Siegfried M. Rump

Published in: Dagstuhl Seminar Proceedings, Volume 9471, Computer-assisted proofs - tools, methods and applications (2010)

Abstract
From November 15-20, 2009, the Dagstuhl seminar on "Computer-assisted proofs - tools, methods and applications" continued a series of previous successful seminars. Participants from 10 different countries presented recent results in verification methods, computer algebra, and other computer-assisted-proof related areas. We had lively talks and discussions, during the regular times for talks, during meals and afterwards. In the following links to abstracts and/or the presentation are given were applicable.
Cite as

Malcolm B. Brown, Erich Kaltofen, Shin'ichi Oishi, and Siegfried M. Rump. 09471 Executive Summary – Computer-assisted proofs - tools, methods and applications. In Computer-assisted proofs - tools, methods and applications. Dagstuhl Seminar Proceedings, Volume 9471, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{brown_et_al:DagSemProc.09471.2,
  author =	{Brown, Malcolm B. and Kaltofen, Erich and Oishi, Shin'ichi and Rump, Siegfried M.},
  title =	{{09471 Executive Summary – Computer-assisted proofs - tools, methods and applications}},
  booktitle =	{Computer-assisted proofs - tools, methods and applications},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9471},
  editor =	{B. Malcolm Brown and Erich Kaltofen and Shin'ichi Oishi and Siegfried M. Rump},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.09471.2},
  URN =		{urn:nbn:de:0030-drops-25316},
  doi =		{10.4230/DagSemProc.09471.2},
  annote =	{Keywords: Verification methods, computer algebra, computer-assisted proofs}
}
Document
DOI: 10.4230/DagSemProc.09471.3
Interval Approaches to Reliable Control of Dynamical Systems

Authors: Andreas Rauh and Ekaterina Auer

Published in: Dagstuhl Seminar Proceedings, Volume 9471, Computer-assisted proofs - tools, methods and applications (2010)

Abstract
Recently, we presented an implementation of interval-based algorithms which can be applied in real-time to control dynamical processes and to estimate internal states and disturbances. The approach is based on verified methods for sets of algebraic equations, ordinary differential equations as well as differential-algebraic equations. Due to this fact, the same program code can be used for two different tasks. On the one hand, we can use it online to estimate non-measurable internal system states which are necessary for nonlinear model-based control strategies. On the other hand, we can verify the admissibility and feasibility of these control strategies offline. Although we use the same code for the online and offline tasks, there is an important difference between them. While the computing time is of minor importance in offline applications, we have to guarantee that the necessary online computations are completed successfully in a predefined time interval. For that reason, the role of verification is slightly different depending on the task. In offline applications, our goal is to compute tightest possible bounds for the sets of all solutions to the control problem under consideration. In contrast to that, we restrict the online mode to a search for a single solution that matches all demands on feasibility of control inputs and admissibility of the trajectories of the state variables in a reliable way. To highlight the practical applicability of the underlying computational routines, we present the following cases for the use of verified solvers in real-time [1-3]. Case 1: Direct computation of feedforward control strategies with the help of differential-algebraic equation solvers. In this application, both verified and non-verified solvers can be used to determine open-loop control strategies for a dynamical system such that its output coincides with a predefined time response within given tolerances. This procedure corresponds to a numerical inversion of the dynamics of the system to be controlled. In this case, verified solvers are used to prove the existence of a control law within given physical bounds for the admissible range of the system inputs. Case 2: If measured data and their time derivatives are available, the same procedures as in case 1 can be used to estimate non-measured state variables as well as non-measurable disturbances. Since the verified algorithms used in this context are capable of propagating bounded measurement uncertainties, the quality of the state and disturbance estimates can be expressed in terms of the resulting interval widths. Moreover, assumptions about the parameters and the structure of the underlying model can be verified. Case 3: Routines for verified sensitivity analysis provide further information on the influence of variations of control inputs on the trajectories of the state variables. We present novel procedures implementing a sensitivity-based framework for model-predictive control. These procedures can be integrated directly in a feedback control structure. Sometimes it is necessary to combine verified and non-verified algorithms to solve a given control problem. In this case, it is important to certify the results of the algorithm appropriately. Based on the four-tier hierarchy presented in earlier works [4], we develop a measure for characterizing such mixed approaches. The presentation is concluded with simulation and experimental results for the example of temperature control of a distributed heating system. [1] Rauh, Andreas; Auer, Ekaterina: Applications of Verified DAE Solvers in Engineering, Intl. Workshop on Verified Computations and Related Topics, COE Lecture Note Vol. 15: Kyushu University, pp. 88-96, Karlsruhe, Germany, 2009. [2] Rauh, Andreas; Menn, Ingolf; Aschemann, Harald: Robust Control with State and Disturbance Estimation for Distributed Parameter Systems, Proc. of 15th Intl. Workshop on Dynamics and Control 2009, pp. 135-142, Tossa de Mar, Spain, 2009. [3] Rauh, Andreas; Auer, Ekaterina; Aschemann, Harald: Real-Time Application of Interval Methods for Robust Control of Dynamical Systems, CD-Proc. of IEEE Intl. Conference on Methods and Models in Automation and Robotics MMAR 2009, Miedzyzdroje, Poland, 2009. [4] Auer, Ekaterina; Luther, Wolfram: Numerical Verification Assessment in Computational Biomechanics, in A. Cuyt, W. Krämer, W. Luther, P. Markstein: Numerical Validation in Current Hardware Architectures, LNCS 5492, pp. 145-160, Springer-Verlag, Berlin, Heidelberg, 2009.
Cite as

Andreas Rauh and Ekaterina Auer. Interval Approaches to Reliable Control of Dynamical Systems. In Computer-assisted proofs - tools, methods and applications. Dagstuhl Seminar Proceedings, Volume 9471, pp. 1-28, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{rauh_et_al:DagSemProc.09471.3,
  author =	{Rauh, Andreas and Auer, Ekaterina},
  title =	{{Interval Approaches to Reliable Control of Dynamical Systems}},
  booktitle =	{Computer-assisted proofs - tools, methods and applications},
  pages =	{1--28},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9471},
  editor =	{B. Malcolm Brown and Erich Kaltofen and Shin'ichi Oishi and Siegfried M. Rump},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.09471.3},
  URN =		{urn:nbn:de:0030-drops-25120},
  doi =		{10.4230/DagSemProc.09471.3},
  annote =	{Keywords: Robust control, Ordinary differential equations, Differential-algebraic equations}
}
Document
DOI: 10.4230/DagSemProc.09471.4
Verification and Validation for Femur Prosthesis Surgery

Authors: Ekaterina Auer, Roger Cuypers, Eva Dyllong, Stefan Kiel, and Wolfram Luther

Published in: Dagstuhl Seminar Proceedings, Volume 9471, Computer-assisted proofs - tools, methods and applications (2010)

Abstract
In this paper, we describe how verified methods we are developing in the course of the project TellHim&S (Interval Based Methods For Adaptive Hierarchical Models In Modeling And Simulation Systems) can be applied in the context of the biomechanical project PROREOP (Development of a new prognosis system to optimize patient-specific pre- operative surgical planning for the human skeletal system). On the one hand, it includes the use of verified hierarchical structures for reliable geometric modeling, object decomposition, distance computation and path planning. On the other hand, we cover such tasks as verification and validation assessment and propagation of differently described uncertainties through system models in engineering or mechanics.
Cite as

Ekaterina Auer, Roger Cuypers, Eva Dyllong, Stefan Kiel, and Wolfram Luther. Verification and Validation for Femur Prosthesis Surgery. In Computer-assisted proofs - tools, methods and applications. Dagstuhl Seminar Proceedings, Volume 9471, pp. 1-22, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2010)

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@InProceedings{auer_et_al:DagSemProc.09471.4,
  author =	{Auer, Ekaterina and Cuypers, Roger and Dyllong, Eva and Kiel, Stefan and Luther, Wolfram},
  title =	{{Verification and Validation for Femur Prosthesis Surgery}},
  booktitle =	{Computer-assisted proofs - tools, methods and applications},
  pages =	{1--22},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2010},
  volume =	{9471},
  editor =	{B. Malcolm Brown and Erich Kaltofen and Shin'ichi Oishi and Siegfried M. Rump},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.09471.4},
  URN =		{urn:nbn:de:0030-drops-25133},
  doi =		{10.4230/DagSemProc.09471.4},
  annote =	{Keywords: Graphical interface construction, superquadrics, 3D modeling, biomedical engineering}
}
Document
DOI: 10.4230/DagSemProc.06271.4
Bounds and algebraic algorithms in differential algebra: the ordinary case

Authors: Marc Moreno Maza, Oleg Golubitsky, Marina V. Kondratieva, and Alexey Ovchinnikov

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
Consider the Rosenfeld-Groebner algorithm for computing a regular decomposition of a radical differential ideal generated by a set of ordinary differential polynomials. This algorithm inputs a system of differential polynomials and a ranking on derivatives and constructs finitely many regular systems equivalent to the original one. The property of regularity allows to check consistency of the systems and membership to the corresponding differential ideals. We propose a bound on the orders of derivatives occurring in all intermediate and final systems computed by the Rosenfeld-Groebner algorithm and outline its proof. We also reduce the problem of conversion of a regular decomposition of a radical differential ideal from one ranking to another to a purely algebraic problem.
Cite as

Marc Moreno Maza, Oleg Golubitsky, Marina V. Kondratieva, and Alexey Ovchinnikov. Bounds and algebraic algorithms in differential algebra: the ordinary case. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-9, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2007)

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@InProceedings{morenomaza_et_al:DagSemProc.06271.4,
  author =	{Moreno Maza, Marc and Golubitsky, Oleg and Kondratieva, Marina V. and Ovchinnikov, Alexey},
  title =	{{Bounds and algebraic algorithms in differential algebra: the ordinary case}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--9},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2007},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.4},
  URN =		{urn:nbn:de:0030-drops-10219},
  doi =		{10.4230/DagSemProc.06271.4},
  annote =	{Keywords: Differential algebra, Rosenfeld Groebner Algorithm}
}
Document
DOI: 10.4230/DagSemProc.06271.15
Two Families of Algorithms for Symbolic Polynomials

Authors: Stephen M. Watt

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
We wish to work with polynomials where the exponents are not known in advance, such as $x^{2n} - 1$. There are various operations we will want to be able to do, such as squaring the value to get $x^{4n}-2x^{2n}+1$, or differentiating it to get $2nx^{2n-1}$. Expressions of this sort arise frequently in practice, for example in the analysis of algorithms, and it is very difficult to work with them effectively in current computer algebra systems. We consider the case where multivariate polynomials can have exponents which are themselves integer-valued multivariate polynomials, and we present algorithms to compute their GCD and factorization. The algorithms fall into two families: algebraic extension methods and interpolation methods. The first family of algorithms uses the algebraic independence of $x$, $x^n$, $x^{n^2}$, $x^{nm}, etc, to solve related problems with more indeterminates. Some subtlety is needed to avoid problems with fixed divisors of the exponent polynomials. The second family of algorithms uses evaluation and interpolation of the exponent polynomials. While these methods can run into unlucky evaluation points, in many cases they can be more appealing. Additionally, we also treat the case of symbolic exponents on rational coefficients (e.g. $4^{n^2+n}-81$) and show how to avoid integer factorization.
Cite as

Stephen M. Watt. Two Families of Algorithms for Symbolic Polynomials. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-20, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{watt:DagSemProc.06271.15,
  author =	{Watt, Stephen M.},
  title =	{{Two Families of Algorithms for Symbolic Polynomials}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--20},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.15},
  URN =		{urn:nbn:de:0030-drops-7933},
  doi =		{10.4230/DagSemProc.06271.15},
  annote =	{Keywords: Computer algebra, symbolic computation, factorization, gcd, symbolic exponents}
}
Document
DOI: 10.4230/DagSemProc.06271.1
06271 Abstracts Collection – Challenges in Symbolic Computation Software

Authors: Wolfram Decker, Mike Dewar, Erich Kaltofen, and Stephen M. Watt

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
From 02.07.06 to 07.07.06, the Dagstuhl Seminar 06271 ``Challenges in Symbolic Computation Software'' was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl. During the seminar, several participants presented their current research, and ongoing work and open problems were discussed. Abstracts of the presentations given during the seminar as well as abstracts of seminar results and ideas are put together in this paper. The first section describes the seminar topics and goals in general. Links to extended abstracts or full papers are provided, if available.
Cite as

Wolfram Decker, Mike Dewar, Erich Kaltofen, and Stephen M. Watt. 06271 Abstracts Collection – Challenges in Symbolic Computation Software. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{decker_et_al:DagSemProc.06271.1,
  author =	{Decker, Wolfram and Dewar, Mike and Kaltofen, Erich and Watt, Stephen M.},
  title =	{{06271 Abstracts Collection – Challenges in Symbolic Computation Software}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--16},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.1},
  URN =		{urn:nbn:de:0030-drops-7814},
  doi =		{10.4230/DagSemProc.06271.1},
  annote =	{Keywords: Symbolic computation, computer algebra, computational algebraic geometry, combinatorial methods in algebra, hybrid, symbolic-numerical methods, algorithm design, symbolic computation languages, systems and user interfaces}
}
Document
DOI: 10.4230/DagSemProc.06271.13
Pivot-Free Block Matrix Inversion

Authors: Stephen M. Watt

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
We present a pivot-free deterministic algorithm for the inversion of block matrices. The method is based on the Moore-Penrose inverse and is applicable over certain general classes of rings. This improves on previous methods that required at least one invertible on-diagonal block, and that otherwise required row- or column-based pivoting, disrupting the block structure. Our method is applicable to any invertible matrix and does not require any particular blocks to invertible. This is achieved at the cost of two additional specialized matrix multiplications and, in some cases, requires the inversion to be performed in an extended ring.
Cite as

Stephen M. Watt. Pivot-Free Block Matrix Inversion. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{watt:DagSemProc.06271.13,
  author =	{Watt, Stephen M.},
  title =	{{Pivot-Free Block Matrix Inversion}},
  booktitle =	{Challenges in Symbolic Computation Software},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.13},
  URN =		{urn:nbn:de:0030-drops-7806},
  doi =		{10.4230/DagSemProc.06271.13},
  annote =	{Keywords: Linear algebra, block matrices, matrix inverse}
}
Document
DOI: 10.4230/DagSemProc.06271.2
06271 Executive Summary - Challenges in Symbolic Computation Software

Authors: Wolfram Decker, Mike Dewar, Erich Kaltofen, and Stephen M. Watt

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
Symbolic computation software allows mathematicians, scientists, engineers, or educators to deal with elaborate calculations using a computer. The applications range from introducing the experimental method in fields of pure mathematics to practical applications, for instance, in cryptology, robotics, or signal theory. The software includes mainstream commercial products such as Maple or Mathematica and highly specialized, public domain systems such as CoCoa, Macaulay2, or Singular. Symbolic computation software implements a variety of sophisticated algorithms on polynomials, matrices, combinatorial structures, and other mathematical objects in a multitude of different dense, sparse, or implicit (black box) representations. The subject of the seminar was innovation in algorithms and software, bringing algorithm designers, software builders, and software users together.
Cite as

Wolfram Decker, Mike Dewar, Erich Kaltofen, and Stephen M. Watt. 06271 Executive Summary - Challenges in Symbolic Computation Software. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-2, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{decker_et_al:DagSemProc.06271.2,
  author =	{Decker, Wolfram and Dewar, Mike and Kaltofen, Erich and Watt, Stephen M.},
  title =	{{06271 Executive Summary - Challenges in Symbolic Computation Software}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--2},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.2},
  URN =		{urn:nbn:de:0030-drops-7778},
  doi =		{10.4230/DagSemProc.06271.2},
  annote =	{Keywords: Symbolic computation, computer algebra, computational algebraic geometry, combinatorial methods in algebra, hybrid symbolic-numerical methods, algori}
}
Document
DOI: 10.4230/DagSemProc.06271.3
Adaptive Triangular System Solving

Authors: Jean-Guillaume Dumas, Clément Pernet, and Jean-Louis Roch

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
Large-scale applications and software systems are getting increasingly complex. To deal with this complexity, those systems must manage themselves in accordance with high-level guidance from humans. Adaptive and hybrid algorithms enable this self-management of resources and structured inputs. In this talk, we first propose a classification of the different notions of adaptivity. For us, an algorithm is adaptive (or a poly-algorithm) when there is a choice at a high level between at least two distinct algorithms, each of which could solve the same problem. The choice is strategic, not tactical. It is motivated by an increase of the performance of the execution, depending on both input/output data and computing resources. Then we propose a new adaptive algorithm for the exact simultaneous resolution of several triangular systems over finite fields. The resolution of such systems is e.g. one of the two main operations in block Gaussian elimination. For solving triangular systems over finite fields, the block algorithm reduces to matrix multiplication and achieves the best known algebraic complexity. Exact matrix multiplication, together with matrix factorizations, over finite fields can now be performed at the speed of the highly optimized numerical BLAS routines. This has been established by the FFLAS and FFPACK libraries. In this talk we propose several practicable variants solving these systems: a pure recursive version, a reduction to the numerical dtrsm routine and a delaying of the modulus operation. Then a cascading scheme is proposed to merge these variants into an adaptive sequential algorithm. We then propose a parallelization of this resolution. The adaptive sequential algorithm is not the best parallel algorithm since its recursion induces a dependancy. A better parallel algorithm would be to first invert the matrix and then to multiply this inverse by the right hand side. Unfortunately the latter requires more total operations than the adaptive algorithm. We thus propose a coupling of the sequential algorithm and of the parallel one in order to get the best performances on any number of processors. The resulting cascading is then an adaptation to resources. This shows that the same process has been used both for adaptation to data and to resources. We thus propose a generic framework for the automatic adaptation of algorithms using recursive cascading.
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Jean-Guillaume Dumas, Clément Pernet, and Jean-Louis Roch. Adaptive Triangular System Solving. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-18, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{dumas_et_al:DagSemProc.06271.3,
  author =	{Dumas, Jean-Guillaume and Pernet, Cl\'{e}ment and Roch, Jean-Louis},
  title =	{{Adaptive Triangular System Solving}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--18},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.3},
  URN =		{urn:nbn:de:0030-drops-7704},
  doi =		{10.4230/DagSemProc.06271.3},
  annote =	{Keywords: Adaptive and hybrid algorithms; triangular system solving; parallel and sequential degenerations}
}
Document
DOI: 10.4230/DagSemProc.06271.5
Challenges in Computational Commutative Algebra

Authors: John Abbott

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
In this paper we consider a number of challenges from the point of view of the CoCoA project one of whose tasks is to develop software specialized for computations in commutative algebra. Some of the challenges extend considerably beyond the boundary of commutative algebra, and are addressed to the computer algebra community as a whole.
Cite as

John Abbott. Challenges in Computational Commutative Algebra. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-12, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{abbott:DagSemProc.06271.5,
  author =	{Abbott, John},
  title =	{{Challenges in Computational Commutative Algebra}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--12},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.5},
  URN =		{urn:nbn:de:0030-drops-7682},
  doi =		{10.4230/DagSemProc.06271.5},
  annote =	{Keywords: Academic recognition implementation OpenMath CoCoA}
}
Document
DOI: 10.4230/DagSemProc.06271.6
Computation of the Minimal Associated Primes

Authors: Santiago Laplagne

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
Solving systems of polynomial equations is a main task in Computer Algebra, although the precise meaning of what is an acceptable solution depends on the context. In this talk, we interpret it as finding the minimal associated primes of the ideal generated by the polynomials. Geometrically, this is equivalent to decompose the set of solutions into its irreducible components. We study the existing algorithms, and propose some modifications. A common technique used is to reduce the problem to the zero dimensional case. In a paper by Gianni, Trager and Zacharias they use this technique, combined with the splitting tool $I = (I : h^infty) cap langle I, h^m angle$ for some specific polynomial $h$ and integer $m$. This splitting introduces a number of redundant components that are not part of the original ideal. In the algorithm we present here, we use the reduction to the zero dimensional case, but we avoid working with the ideal $langle I, h^m angle$. As a result, when the ideal has components of different dimensions, our algorithm is usually more efficient.
Cite as

Santiago Laplagne. Computation of the Minimal Associated Primes. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-6, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{laplagne:DagSemProc.06271.6,
  author =	{Laplagne, Santiago},
  title =	{{Computation of the Minimal Associated Primes}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--6},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.6},
  URN =		{urn:nbn:de:0030-drops-7741},
  doi =		{10.4230/DagSemProc.06271.6},
  annote =	{Keywords: Minimal associated primes, groebner basis, polynomail equations, radical}
}
Document
DOI: 10.4230/DagSemProc.06271.7
Computational Aspects of the Resolution of Singularities

Authors: Anne Frühbis-Krüger

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
The task of resolution of singularities has been one of the central topics in Algebraic Geometry for many decades. After results in low dimension in the first half of the 20th century, it was Hironaka's monumental article in 1964 which solved the porblem in the general case in chareacteristic zero. The case of characteristic $p > 0$ is still unsolved except in partial results in low dimension. But Hironaka's proof did not put an end to the interest in characteric zero, instead it shifted the focus toward the task of finding a more constructive approach. Such algorithmic approaches appeared at the end of the 1980's independently by Villamayor and by Bierstone and Milman. In this talk we consider the computational tasks arising from Villamayor's algorithm and present an implementation.
Cite as

Anne Frühbis-Krüger. Computational Aspects of the Resolution of Singularities. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-8, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{fruhbiskruger:DagSemProc.06271.7,
  author =	{Fr\"{u}hbis-Kr\"{u}ger, Anne},
  title =	{{Computational Aspects of the Resolution of Singularities}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--8},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.7},
  URN =		{urn:nbn:de:0030-drops-7713},
  doi =		{10.4230/DagSemProc.06271.7},
  annote =	{Keywords: Resolution of Singularities, algorithmic desingularization,}
}
Document
DOI: 10.4230/DagSemProc.06271.8
Coxeter Lattice Paths

Authors: Thomas J. Ashby, Anthony D. Kennedy, and Stephen M. Watt

Published in: Dagstuhl Seminar Proceedings, Volume 6271, Challenges in Symbolic Computation Software (2006)

Abstract
This talk concerns generating code for running computationally intensive numerical lattice QCD simulations on large parallel computers, using an approach based on the theory of Coxeter groups. Many physical systems have inherent symmetry, and this is usually implicit in the calculations needed to simulate them using discrete approximations, and thus in the associated code. By reversing this and basing the generation of code on the symmetry group of the lattice in question, we arrive at a very natural way of generating and reasoning about programs. The principal aim is a formal way of representing lattices and the paths on these lattices that correspond to the required calculations. This foundation allows the creation and manipulation of lattices and paths to be automated, obviating what can be a labour-intensive and errorprone task. In more detail, a method will be given for representing the points of a regular lattice as elements of the translation subgroup of an affine Coxeter group, by finding the subgroup generators starting from the Coxeter graph of the affine group. Similarly, step sequences are derived as words in the free group generated by the translation subgroup generators themselves. We introduce code generation techniques and the automation of two code optimisations; the grouping of paths into equivalence classes, and the factoring out of common path segments. The latter technique reduces the amount of communication necessary between nodes, and is thus likely to be important in practice.
Cite as

Thomas J. Ashby, Anthony D. Kennedy, and Stephen M. Watt. Coxeter Lattice Paths. In Challenges in Symbolic Computation Software. Dagstuhl Seminar Proceedings, Volume 6271, pp. 1-14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2006)

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@InProceedings{ashby_et_al:DagSemProc.06271.8,
  author =	{Ashby, Thomas J. and Kennedy, Anthony D. and Watt, Stephen M.},
  title =	{{Coxeter Lattice Paths}},
  booktitle =	{Challenges in Symbolic Computation Software},
  pages =	{1--14},
  series =	{Dagstuhl Seminar Proceedings (DagSemProc)},
  ISSN =	{1862-4405},
  year =	{2006},
  volume =	{6271},
  editor =	{Wolfram Decker and Mike Dewar and Erich Kaltofen and Stephen Watt},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagSemProc.06271.8},
  URN =		{urn:nbn:de:0030-drops-7695},
  doi =		{10.4230/DagSemProc.06271.8},
  annote =	{Keywords: Parallel computing, code generation, Coxeter groups, regular lattices, lattice paths, path optimisation}
}
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