11/29/2016 FPSAC 2009

https://www.risc.jku.at/conferences/fpsac2009/?content=program 1/6

Research Institute for Symbolic Computation Johannes Kepler University Linz

21st International Conference on Formal Power Series

& Algebraic Combinatorics

July 20-24, 2009, Hagenberg, AustriaNews General Dates Committees Submission Participants Program Travel Photos Links

Tentative Schedule

     

Sunday Monday Tuesday Wednesday Thursday Friday08:30–09:00

 

Registration       

09:00–09:30 Barvinok Singer Erdmann Welker Yee09:30–10:0010:00–10:30 Ardila et al Coffee Coffee Chapuy Thiem10:30–11:00 Coffee Bostan/Kauers Bürgisser/Ikenmeyer Coffee Coffee11:00–11:30 Ardila/Postnikov Levine Serrano Kallipoliti Buan et al11:30–12:00 Bousquet-Melou et al

Poster 2 SoftwareAguiar et al Woo

12:00–12:30 Eriksen et al Musiker/Schiffler Fink/Giraldo     

Lunch Lunch Lunch Lunch Lunch     

     

14:00–14:30 Salvy Sottile Nesetril

Free Afternoon

Schneider14:30–15:0015:00–15:30

Registration

Coffee Coffee Coffee Coffee15:30–16:00 Lenart Mastnak/Nica Diao et al Albenque/Nadeau16:00–16:30 Assaf et al Dolega et al Helleloid et al Berg16:30–17:00

Poster 1

Excursion

Hersh et al Fourier et al17:00–17:30

      Poster 3

 

17:30–18:00   

 

     

Reception    

     

     

 Banquet     

     

     

     

Sunday

Sun 15.00–18.00 Registration at the conference office

Sun 17.00&ndash Welcome reception at the Research Institute for Symbolic Computation (Venue: GemeindesaalHagenberg, Castle.)

Monday

Mon 08.30–09.00 Registration at the conference office

Mon 09.00–10.00 Alexander Barvinok (University of Michigan, USA) Integer points in higher-dimensional polyhedra: counting and sampling I plan to discuss a new approach to counting and sampling of integer points in higher-dimensional

11/29/2016 FPSAC 2009

https://www.risc.jku.at/conferences/fpsac2009/?content=program 2/6

polyhedra. The idea is to approximate the counting probability measure on the set of the integerpoints in a polyhedron by the maximum entropy measure on the set of all non-negative integervectors with the expectation in the polyhedron. Applications to contingency tables (non-negativeinteger matrices with prescribed row and column sums) will be discussed. The talk is based on ajoint work with J. Hartigan.

Mon 10.00–10.30 Federico Ardila, Carolina Benedetti and Jeffrey Doker Matroid Polytopes and Their Volumes

Mon 10.30–11.00 Coffee break

Mon 11.00–11.30 Federico Ardila and Alex Postnikov Combinatorics and geometry of power ideals

Mon 11.30–12.00 Mireille Bousquet-Melou, Anders Claesson, Mark Dukes and Sergey Kitaev Unlabeled (2+2)-free posets, ascent sequences and pattern avoiding permutations

Mon 12.00–12.30 Niklas Eriksen, Ragnar Freij and Johan Wästlund Enumeration of derangements with descents in prescribed positions

Mon 12.00–14.00 Lunch break

Mon 14.00–15.00 Bruno Salvy (INRIA Rocquencourt, France)Automatic proof of identities: beyond A=B In the past 30 years, computer algebra has made a lot of progress in the design of algorithmsoperating on mathematical objects. In particular, a few simple but fruitful ideas make it possible tocompute sums or integrals of a wide variety of functions. Early work concentrated onhypergeometric identities. This was generalized by Zeilberger to deal with what he called"holonomic" systems. Recently, we generalized this further In a joint work with Chyzak andKauers so that even more functions and sequences can be handled automatically. The talk willfocus on the basic principles that underly all these algorithms.

Mon 15.00–15.30 Coffee break

Mon 15.30–16.00 Cristian Lenart Combinatorial Formulas for Macdonald and Hall-Littlewood Polynomials

Mon 16.00–16.30 Sami Assaf, Persi Diaconis and K. Soundararajan Riffle shuffles of a deck with repeated cards

Mon 16.30–18.00 Poster session

Tuesday

Tue 09.00–10.00 Michael F. Singer (North Carolina State University, USA)Differential Groups and the Gamma Function I will develop a Galois theory of linear difference equations where the Galois groups are lineardifferential groups that is, groups of matrices whose entries satisfy a fixed set of polynomialdifferential equations. These groups measure the differential dependence among solutions oflinear difference equations. I will show how this theory can be used to reprove Hoelder's Theoremthat the Gamma function satisfies no differential polynomial equation as well as new resultsconcerning differential dependence of solutions of higher order difference equations.

Tue 10.00–10.30 Coffee break

Tue 10.30–11.00 Alin Bostan and Manuel Kauers Automatic Classification of Restricted Lattice Walks

Tue 11.00–11.30 Lionel Levine Chip-Firing And A Devil's Staircase

Tue 11.30–12.30 Poster session

Tue 12.30–14.00 Lunch break

11/29/2016 FPSAC 2009

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Tue 14.00–15.00 Frank Sottile (Texas A&M University, USA) New Hopf Structures on the Planar Binary Trees

Two of the most interesting combinatorial Hopf algebras are the Hopf algebras of permutationsand of planar binary trees. These fit into an interesting commutative diagram involving thesymmetric, noncommutative symmetric, and quasisymmetric functions. They also each have twodifferent bases related by Moebius inversion on a poset which reveal a rich interaction betweentheir algebraic structure and the combinatorics of permutations and of trees. These posets are theedge graphs of the permutahedra and the associahedra, and the algebra structure is also linkedto the structure of these polytopes.

Both the permutahedra and associahedra arise naturally in homotopy theory, and the point ofdeparture for this talk is another family of polytopes, the multiplihedra, which also arose inhomotopy theory. Natural cellular maps from permutahedra to associahedra (which induce mapsof Hopf algebras) factor through the multiplihedra. Restricting this map to their vertices factorizesthe map from permutations to trees. The intermediate objects are certain bi-leveled trees. Weshow how to put algebraic structures on bi-leveled trees so that their linear span M becomes amodule over the Hopf algebra of permutations and a Hopf module algebra over the Hopf algebraof trees. A second basis of M, related to the first via Moebius inversion on the multiplihedra helpsto elucidate these structures. Bi-leveled trees also admit a second structure as a Hopf algebra,and we identify other combinatorial objects between permutations and trees which similarly arerelated to polytopes and admit some Hopf structures. This is joint work with Aaron Lauve andStefan Forcey.

Tue 15.00–15.30 Coffee break

Tue 15.30–16.00 Mitja Mastnak and Alexandru Nica Hopf algebras and the logarithm of the S-transform in free probability

Tue 16.00–16.30 Maciej Dolega, Valentin Féray and Piotr Sniady Characters of symmetric groups in terms of free cumulants and Frobenius coordinates

Tue 16.30– Excursion

Wednesday

Wed 09.00–10.00 Karin Erdmann (University of Oxford, UK)Representations of symmetric groups over prime characteristic Although the irreducible representations of symmetric groups over prime characteristic areparametrized, they are not known in general. This lecture will give an overview over algebraic andcombinatorial tools to understand irreducible representations, especially decomposition numbers.

Wed 10.00–10.30 Coffee break

Wed 10.30–11.00 Peter Bürgisser and Christian Ikenmeyer A max-flow algorithm for positivity of Littlewood-Richardson coefficients

Wed 11.00–11.30 Luis Serrano The shifted plactic monoid

Wed 11.30–12.30 Software session

Cyril Banderier: HolonomAsympt (canceled)Michael Joswig, Benjamin Müller, and Andreas Pfaffenholz: polymakeManuel Kauers: GuessChristoph Koutschan: HolonomicFunctionsCarsten Schneider: SigmaNicolas Thiery and Anne Schilling: sage-combinat

Wed 12.00–14.00 Lunch break

Wed 14.00–15.00 Jaroslav Nesetril (Charles University Prague, Czech Republic)Forbidden paths Finite paths are one of the simplest (and most frequent) mathematical objects. Yet they present a

   

11/29/2016 FPSAC 2009

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surprising rich are particularly from the algebraic and computational point of view. Recentdevelopment in this area will be surveyed.

Wed 15.00–15.30 Coffee break

Wed 15.30–16.00 Yuanan Diao, Gabor Hetyei and Kenneth Hinson Colored Tutte polynomials and composite knots

Wed 16.00–16.30 Geir Helleloid and Fernando Rodriguez-Villegas Counting Quiver Representations over Finite Fields Via Graph Enumeration

Wed 16.30–17.00 Patricia Hersh, John Shareshian and Dennis Stanton The $q=-1$ phenomenon for bounded (plane) partitions via homology concentration

Wed 17.00–18.00 Poster session

Thursday

Thu 09.00–10.00 Volkmar Welker (Philipps-Universität Marburg)Matrices of Generalized Inversions We describe a family of matrices with rows and columns indexed by permutations. The entriesgeneralize the inversion statistics on the symmetric group. These matrices are not only related tothe inversion statistics but also to the Varchenko matrix for the reflection arrangement of thesymmetric group, the matrices of the random to random shuffle and the linear ordering polytope.We show some of the beautiful properties of these matrices. In particular, we study the algebragenerated by the matrices, which can be seen as a subalgebra of the group algebra of thesymmetric group. Finally we describe a generalization of the matrices within the symmetric groupand for general finite Coxeter groups. (this is joint work with Franco Saliola nd Vic Reiner).

Thu 10.00–10.30 Guillaume Chapuy A new combinatorial identity for unicellular maps, via a direct bijective approach

Thu 10.30–11.00 Coffee break

Thu 11.00–11.30 Myrto Kallipoliti The absolute order on the hyperoctahedral group

Thu 11.30–12.00 Marcelo Aguiar, Jean-Christophe Novelli and Jean-Yves Thibon Unital versions of the higher order peak algebras

Thu 12.00–12.30 Gregg Musiker and Ralf Schiffler Cluster algebras of unpunctured surfaces and snake graphs

Thu 12.30–14.00 Lunch break

Thu 14.00–19.00 Free afternoon

Thu 19.00– Conference Banquet

Friday

Fri 09.00–10.00 Ae Ja Yee (Pennsylvania State University, USA)Parity in partitions Parity has played a role in additive number theory, in particular partition identities from thebeginning. In his recent long paper, Andrews began the thorough study of parity questions arisingin partition identities. At the end of the paper, he then listed 15 open problems. In this talk, weshall discuss several new discoveries of Andrews and provide answers to some of his openquestions.

Fri 10.00–10.30 Nathaniel Thiem Branching rules in the ring of superclass functions of unipotent upper-triangular matrices

Fri 10.30–11.00 Coffee break

Fri 11.00–11.30 Aslak Bakke Buan, Idun Reiten and Hugh Thomas

11/29/2016 FPSAC 2009

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m-noncrossing partitons and m-clusters

Fri 11.30–12.00 Alexander Woo Permutations with Kazhdan-Lusztig polynomial P_{id,w}(q)=1+q^h

Fri 12.00–12.30 Alex Fink and Benjamin Iriarte Giraldo Bijections between noncrossing and nonnesting partitions for classical reflection groups

Fri 12.30–14.00 Lunch break

Fri 14.00–15.00 Carsten Schneider (RISC, Johannes Kepler University Linz, Austria)Symbolic Summation and its Application in Particle Physics In this talk we present recent multi-summation algorithms based on our refined difference fieldtheory. We work out how the interplay of the summation paradigms for telescoping, creativetelescoping and recurrence solving can be used to discover and prove combinatorial and specialfunction identities. Special emphasis is put on concrete examples from particle physics that arisein the evaluation of Feynman integrals.

Fri 15.00–15.30 Coffee break

Fri 15.30–16.00 Marie Albenque and Philippe Nadeau Growth functions for a class of monoids

Fri 16.00–16.30 Chris Berg The Ladder Crystal

Fri 16.30–17.00 Ghislain Fourier, Masato Okado and Anne Schilling Perfectness of Kirillov-Reshetikhin crystals for nonexceptional types

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Social Program

Sunday, July 19

17:00 Welcome reception at the Research Institute for Symbolic Computation (RISC). Venue: Gemeindesaal Hagenberg (Castle).

Tuesday, July 21

On Tuesday afternoon, there will be an excursion to the beautiful village Reichenthal, which is located in the north ofUpper Austria (approx. 30 min. bus transfer from Hagenberg). You will visit the mill museum in "Hayrl", where you alsoget an impression of craft in the old days.

At 7:00 p.m. there will be a reception in the castle Waldenfels, which is a 5 minutes walk away from the mill museum. Thecastle Schloss Waldenfels was built around 1380 and combines several epochs; the Middle Ages, Renaissance andBaroque. Since 1636, the castle is privately-owned by the family "Grundemann von Falkenberg". Nowadays, the castleserves still as family estate and popular venue.

11/29/2016 FPSAC 2009

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In the frame of the reception, Mr. Dominik Grundemann-Falkenberg, owner of the castle, will give an insight into thehistory of the castle and of the earl family "Grundemann von Falkenberg". If interested, you have the opportunity to enjoya short guided tour through the castle. You can also take a virtual flight around the castle right now.

At around 7:30 p.m. Peter Paule will open the dinner, which is in form of a rich buffet of specialities of the region"Mühlviertel".

Around 9:30 p.m. we plan the bus transfer back to Hagenberg.

Note: You must register for the excursion at the time of registering for the conference. The costs for the excursionincluding transport, welcome reception at the castle "Schloss Waldenfels"- and dinner (NOT including beverages) are 30Euro per person.

Thursday, July 23

In the free afternoon you might want to use the opportunity and go for a sightseeing tour through Linz, the EuropeanCapital of Culture 2009. For your convenience a selection of the program and an overview of the historical buildings inLinz can be found in this folder. In the evening, the banquet will take place on board of the MS Anton Bruckner. The boat will depart from Linz and sail upto Ottensheim, return and pass Linz which you will be able to admire by night, then up to Steyregg bridge and finally backto Linz. A bus transfer from Hagenberg to Linz and back will be organised.

Note: You must register for the banquet (which includes the boat trip) at the time of registering for the conference.

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