5 Search Results for "Frank, Ulrich"


Document
PACE Solver Description
PACE Solver Description: Exact (GUTHMI) and Heuristic (GUTHM)

Authors: Alexander Leonhardt, Holger Dell, Anselm Haak, Frank Kammer, Johannes Meintrup, Ulrich Meyer, and Manuel Penschuck

Published in: LIPIcs, Volume 285, 18th International Symposium on Parameterized and Exact Computation (IPEC 2023)


Abstract
Twin-width (tww) is a parameter measuring the similarity of an undirected graph to a co-graph [Édouard Bonnet et al., 2022]. It is useful to analyze the parameterized complexity of various graph problems. This paper presents two algorithms to compute the twin-width and to provide a contraction sequence as witness. The two algorithms are motivated by the PACE 2023 challenge, one for the exact track and one for the heuristic track. Each algorithm produces a contraction sequence witnessing (i) the minimal twin-width admissible by the graph in the exact track (ii) an upper bound on the twin-width as tight as possible in the heuristic track. Our heuristic algorithm relies on several greedy approaches with different performance characteristics to find and improve solutions. For large graphs we use locality sensitive hashing to approximately identify suitable contraction candidates. The exact solver follows a branch-and-bound design. It relies on the heuristic algorithm to provide initial upper bounds, and uses lower bounds via contraction sequences to show the optimality of a heuristic solution found in some branch.

Cite as

Alexander Leonhardt, Holger Dell, Anselm Haak, Frank Kammer, Johannes Meintrup, Ulrich Meyer, and Manuel Penschuck. PACE Solver Description: Exact (GUTHMI) and Heuristic (GUTHM). In 18th International Symposium on Parameterized and Exact Computation (IPEC 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 285, pp. 37:1-37:7, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{leonhardt_et_al:LIPIcs.IPEC.2023.37,
  author =	{Leonhardt, Alexander and Dell, Holger and Haak, Anselm and Kammer, Frank and Meintrup, Johannes and Meyer, Ulrich and Penschuck, Manuel},
  title =	{{PACE Solver Description: Exact (GUTHMI) and Heuristic (GUTHM)}},
  booktitle =	{18th International Symposium on Parameterized and Exact Computation (IPEC 2023)},
  pages =	{37:1--37:7},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-305-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{285},
  editor =	{Misra, Neeldhara and Wahlstr\"{o}m, Magnus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.IPEC.2023.37},
  URN =		{urn:nbn:de:0030-drops-194563},
  doi =		{10.4230/LIPIcs.IPEC.2023.37},
  annote =	{Keywords: PACE 2023 Challenge, Heuristic, Exact, Twin-Width}
}
Document
Brief Announcement
Brief Announcement: A Tight Lower Bound for Clock Synchronization in Odd-Ary M-Toroids

Authors: Reginald Frank and Jennifer L. Welch

Published in: LIPIcs, Volume 121, 32nd International Symposium on Distributed Computing (DISC 2018)


Abstract
In this paper we show a tight closed-form expression for the optimal clock synchronization in k-ary m-cubes with wraparound, where k is odd. This is done by proving a lower bound of 1/4um (k-1/k), where k is the (odd) number of processes in each of the m dimensions, and u is the uncertainty in delay on every link. Our lower bound matches the previously known upper bound.

Cite as

Reginald Frank and Jennifer L. Welch. Brief Announcement: A Tight Lower Bound for Clock Synchronization in Odd-Ary M-Toroids. In 32nd International Symposium on Distributed Computing (DISC 2018). Leibniz International Proceedings in Informatics (LIPIcs), Volume 121, pp. 47:1-47:3, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@InProceedings{frank_et_al:LIPIcs.DISC.2018.47,
  author =	{Frank, Reginald and Welch, Jennifer L.},
  title =	{{Brief Announcement: A Tight Lower Bound for Clock Synchronization in Odd-Ary M-Toroids}},
  booktitle =	{32nd International Symposium on Distributed Computing (DISC 2018)},
  pages =	{47:1--47:3},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-092-7},
  ISSN =	{1868-8969},
  year =	{2018},
  volume =	{121},
  editor =	{Schmid, Ulrich and Widder, Josef},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/LIPIcs.DISC.2018.47},
  URN =		{urn:nbn:de:0030-drops-98360},
  doi =		{10.4230/LIPIcs.DISC.2018.47},
  annote =	{Keywords: Clock synchronization, Lower bound, k-ary m-toroid}
}
Document
Multi-Level Modelling (Dagstuhl Seminar 17492)

Authors: João Paulo A. Almeida, Ulrich Frank, and Thomas Kühne

Published in: Dagstuhl Reports, Volume 7, Issue 12 (2018)


Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 17492 "Multi-Level Modelling". This seminar brought together researchers and industry practitioners from the fields of conceptual modeling, ontologies, and formal foundations to discuss and share the benefits of Multi-Level Modelling (MLM), to develop an agreement on MLM terminology and scope, and to drive future research directions in MLM. Some foundational presentations were given by the seminar organizers to ground the discussions and provide an initial set of open questions which would lead to the formation of the working groups. In addition, six industry representatives gave talks explaining the needs, challenges, utility, and possible issues with adoption of MLM in industry. Based on the original seminar goals, the talks, and the resulting discussions, four working groups were established to investigate: the formal and ontological "Foundations"of MLM; promising "Applications" and potential evaluation criteria for MLM methods; the "Dynamic Aspects" of MLM, such as processes and behaviour; and, the use of and impact on "Model Transformations" in the context of MLM.

Cite as

João Paulo A. Almeida, Ulrich Frank, and Thomas Kühne. Multi-Level Modelling (Dagstuhl Seminar 17492). In Dagstuhl Reports, Volume 7, Issue 12, pp. 18-49, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2018)


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@Article{almeida_et_al:DagRep.7.12.18,
  author =	{Almeida, Jo\~{a}o Paulo A. and Frank, Ulrich and K\"{u}hne, Thomas},
  title =	{{Multi-Level Modelling (Dagstuhl Seminar 17492)}},
  pages =	{18--49},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2018},
  volume =	{7},
  number =	{12},
  editor =	{Almeida, Jo\~{a}o Paulo A. and Frank, Ulrich and K\"{u}hne, Thomas},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.7.12.18},
  URN =		{urn:nbn:de:0030-drops-86758},
  doi =		{10.4230/DagRep.7.12.18},
  annote =	{Keywords: metamodeling, multi-level modeling}
}
Document
Supporting Organizational Efficiency and Agility: Models, Languages and Software Systems (Dagstuhl Seminar 16192)

Authors: Tony Clark, Ulrich Frank, and Vinay Kulkarni

Published in: Dagstuhl Reports, Volume 6, Issue 5 (2016)


Abstract
Organizations are complex systems that need to respond to a variety of changes while operating in a dynamic environment. They involve multiple stakeholders each having a domain-specific perspective that relies on concepts and languages relative to individual information-centric processes, which may lead to undesirable side-effects such as scattered and fractured knowledge about goals, strategies, operational processes etc. This inter-disciplinary seminar analyses how the design, operation and maintenance of organizations can be supported not only with managing their resources and processes efficiently, but also with coping with the digital transformation.

Cite as

Tony Clark, Ulrich Frank, and Vinay Kulkarni. Supporting Organizational Efficiency and Agility: Models, Languages and Software Systems (Dagstuhl Seminar 16192). In Dagstuhl Reports, Volume 6, Issue 5, pp. 31-55, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2016)


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@Article{clark_et_al:DagRep.6.5.31,
  author =	{Clark, Tony and Frank, Ulrich and Kulkarni, Vinay},
  title =	{{Supporting Organizational Efficiency and Agility: Models, Languages and Software Systems (Dagstuhl Seminar 16192)}},
  pages =	{31--55},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2016},
  volume =	{6},
  number =	{5},
  editor =	{Clark, Tony and Frank, Ulrich and Kulkarni, Vinay},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.6.5.31},
  URN =		{urn:nbn:de:0030-drops-67197},
  doi =		{10.4230/DagRep.6.5.31},
  annote =	{Keywords: Digital transformation, DSML, enterprise modelling, enterprise software systems, Organisational action systems}
}
Document
Open Models as a Foundation of Future Enterprise Systems (Dagstuhl Seminar 12131)

Authors: Robert B. France, Ulrich Frank, Andreas Oberweis, Matti Rossi, and Stefan Strecker

Published in: Dagstuhl Reports, Volume 2, Issue 3 (2012)


Abstract
This report documents the program and the outcomes of Dagstuhl Seminar 12131 ``Open Models as a Foundation of Future Enterprise Systems''. Research on open models introduces a new model of collaboration among researchers, developers, and prospective users of reference enterprise models-leading to the prospect of shaping future enterprise systems. This seminar brought together researchers and practitioners with expertise in a broad range of fields including conceptual modelling, model-driven engineering, enterprise systems, software architectures, and modelling tool development. The seminar mixed short presentations on the attendees' perspectives on open models with keynote presentations and working groups on selected research issues. Topics discussed include the shape of future enterprise systems amalgamated with open reference enterprise models, business domains to be addressed in first open models, requirements towards a technical infrastructure as well as organisational issues of open model initiatives. The seminar's discussions benefitted from the different perspectives of attendees on the common topic, raised important new questions on open models, and brought to light overlooked aspects important to future research activities.

Cite as

Robert B. France, Ulrich Frank, Andreas Oberweis, Matti Rossi, and Stefan Strecker. Open Models as a Foundation of Future Enterprise Systems (Dagstuhl Seminar 12131). In Dagstuhl Reports, Volume 2, Issue 3, pp. 67-85, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2012)


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@Article{france_et_al:DagRep.2.3.67,
  author =	{France, Robert  B. and Frank, Ulrich and Oberweis, Andreas and Rossi, Matti and Strecker, Stefan},
  title =	{{Open Models as a Foundation of Future Enterprise Systems (Dagstuhl Seminar 12131)}},
  pages =	{67--85},
  journal =	{Dagstuhl Reports},
  ISSN =	{2192-5283},
  year =	{2012},
  volume =	{2},
  number =	{3},
  editor =	{France, Robert  B. and Frank, Ulrich and Oberweis, Andreas and Rossi, Matti and Strecker, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops-dev.dagstuhl.de/entities/document/10.4230/DagRep.2.3.67},
  URN =		{urn:nbn:de:0030-drops-35379},
  doi =		{10.4230/DagRep.2.3.67},
  annote =	{Keywords: Enterprise Modelling, Enterprise Systems, Reference Model, Meta Modeling, Method Engineering, Information Systems Architectures}
}
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