### PARTICIPANTS

- last update April 17 -

• March 25, 2009: applying for financial aid
• April 10, 2009: submitting a title and abstract for a contributed talk
• April 15, 2009: registration.

January and February registration

Nasser Dastrange - Buena Vista University
 Mon, 26 Jan 2009 09:40:17  CombinaTexas Registration Form is submitted by Dr.  Nasser Dastrange  From: Dr.  Nasser Dastrange  E-Mail: dastrange@bvu.edu  From Position and Institution: Professor of Mathematics at Buena Vista University  Address Line 1: 610, W. 4th. St.  Address Line 2: Storm Lake, Iowa, 50588  Address Line 3:  Contribute Talk: No
Irinel Dragan - UT
 Mon, 26 Jan 2009 19:12:56  CombinaTexas Registration Form is submitted by Dr.  Irinel Dragan  From: Dr.  Irinel Dragan  E-Mail: dragan@uta.edu  From Position and Institution: Professor Emeritus of Mathematics, Univ. of Texas  Address Line 1: University of Texas at Arlington  Address Line 2: Department of Mathematics  Address Line 3: Arlington, Texas 76019-0408  Contribute Talk: Yes <=== CANCEL TALK  Talk Title: On the parallel computation of the individual Value of cooperation in Flow Games  Abstract: The Flow Games have been introduced by Kalai and Zemel (1982). We show a Flow Game, for which we can easily compute the Maximum Flow, for each coalition of owners of the edges, and decide that the total cooperation gives the best results. Then, the fair division of the outcome offered by the grand coalition can be obtained by computing some Value of the Flow Game. The most famous solution is the Shapley Value of the Flow Game. We show how this is a parallel computation, as a result of a formula for the Shapley Value. If we decide to use a Semivalue then we show a similar formula. We called these formulas the "Average per capita" formulas, because they depend only on some averages of worth of coalitions. We illustrate with a numerical game.
Jonathan Gamez - University of Houston (Downtown)
 Tue, 3 Feb 2009 13:41:24  CombinaTexas Registration Form is submitted by Mr.  Jonathan Gamez From: Mr.  Jonathan Gamez E-Mail: j_g12soccer@yahoo.com From Position and Institution: Student at University of Houston - Downtown Address Line 1: One Main Street Address Line 2: Houston, TX 77002 Address Line 3: Contribute Talk: No Talk Title: Abstract:
Colton Magnant - Lehigh University - intends to contribute a talk
 Wed, 4 Feb 2009 21:24:28  CombinaTexas Registration Form is submitted by Dr.  Colton Magnant  From: Dr.  Colton Magnant  E-Mail: com208@lehigh.edu  From Position and Institution: Post-Doc at Lehigh University  Address Line 1: Christmas-Saucon Hall  Address Line 2: 14 E. Packer Ave.  Address Line 3: Bethlehem, PA 18015  Contribute Talk: Yes  Talk Title: Rainbow Ramsey Theory  Abstract: This talk will provide a brief survey of recent rainbow ramsey results and how they relate to the literature.  Classical ramsey theory involves finding monochromatic structures in colored graphs.  Similarly, rainbow ramsey theory involves finding either a monochromatic copy of a graph or a rainbow (totally multicolored) copy of another graph.  For some rainbow graphs, for example the triangle, this question has been reasonably well studied.  For most others, the problem is wide open.
Geir Helleloid - U. of Texas at Austin - intends to contribute a talk
 Mon, 16 Feb 2009 14:15:33 -0600 CombinaTexas Registration Form is submitted by Dr.  Geir Helleloid  From: Dr.  Geir Helleloid  E-Mail: geir@math.utexas.edu  From Position and Institution: Bing Instructor (post-doc), U. of Texas at Austin  Address Line 1: Dept. of Mathematics, UT-Austin  Address Line 2: 1 University Station C1200  Address Line 3: Austin, TX 78712  Contribute Talk: Yes  Talk Title: Recognition and Reconstruction of Vertex-Edge Incidence Graphs  Abstract: In order to study the strong chromatic index of multigraphs, Brualdi and Massey introduced the incidence coloring number, which can be defined as the chromatic number of the vertex-edge incidence graph (VEIG) of a graph. VEIGs are reminiscent of line graphs, and much work has been done on structural characterizations and recognition algorithms for line graphs.  I will discuss an  analogous linear-time recognition algorithm for VEIGs that also permits the reconstruction of a graph from its VEIG.  I will also mention work on a forbidden subgraph characterization of the hereditary family of VEIGs of digraphs.  This is joint work with Stephen Hartke.
Mahir Bilen Can - Tulane University - intends to contribute a talk
 Sat, 21 Feb 2009 21:22:57 CombinaTexas Registration Form is submitted by Dr.  Mahir Bilen Can  From: Dr.  Mahir Bilen Can  E-Mail: mcan@tulane.edu  From Position and Institution: faculty at Tulane University  Address Line 1: 1823 Audubon Street, New Orleans, 70118, LA.  Address Line 2:  Address Line 3:  Contribute Talk: Yes  Talk Title: Symmetric functions and reducutive monoids  Abstract: A J-irreducible reductive monoid is the (Zariski) closure of an irreducible representation of a reductive group $G$. In this talk, we will construct a family of symmetric functions for these monoids following Bergeron - Sottile construction of the (quasi)symmetric functions for a labeled graded poset.
Abraham Martin del Campo - Texas A&M University
 Wed, 11 Feb 2009 16:31:27 CombinaTexas Registration Form is submitted by   Abraham Martin del Campo  From:   Abraham Martin del Campo  E-Mail: asanchez@math.tamu.edu  From Position and Institution: Graduate Student at Texas A&M University  Address Line 1: Department of Mathematics  Address Line 2: Texas A&M University - 3368  Address Line 3: College Station, TX 77843-3368  Contribute Talk: No  Talk Title:  Abstract:
Ken W. Smith - Sam Houston State University - intends to contribute a talk
 Tue, 24 Feb 2009 13:13:37 CombinaTexas Registration Form is submitted by Dr.  Ken W. Smith  From: Dr.  Ken W. Smith  E-Mail: kenwsmith@shsu.edu  From Position and Institution: Faculty, Sam Houston State University  Address Line 1: Department of Mathematics and Statistics, PO Box 2206  Address Line 2: Sam Houston State University  Address Line 3: Huntsville, TX 77341-2206  Request for Support: No  Comment on support:  Contribute Talk: Yes  Talk Title: Rational Idempotents in the Integral Group Ring and Their Applications  Abstract: Given a finite abelian group G, we construct a variety of combinatorial objects in G (such as difference sets and partial difference sets) using the rational idempotents of the group ring  Q[G].  Since combinatorial objects typically live in Z[G], these techniques provide divisibility conditions which dramatically narrow the search space for the combinatorial object.  In some cases, these techniques allow a full enumeration of the combinatorial objects or provide the means for an exhaustive search.  We give an introduction to this "idempotent" approach and provide a number of examples of objects constructed by this method.
Svetlana Poznanovik - Texas A&M University - intends to contribute a talk
 Sat, 28 Feb 2009 09:41:25  CombinaTexas Registration Form is submitted by Ms.  Svetlana Poznanovik  From: Ms.  Svetlana Poznanovik  E-Mail: spoznan@math.tamu.edu  From Position and Institution: graduate student at Texas A&M University  Address Line 1: Department of Mathematics  Address Line 2: Texas A&M University  Address Line 3: College Station, TX 77843-3368  Contribute Talk: Yes  Talk Title: Major Index for 01-Fillings of Moon Polyominoes  Abstract: In my talk I will present a definition for major index on 01-fillings of moon polyominoes. When specialized to certain shapes, this statistic reduces to the major index for permutations and set partitions. We consider the set $\mathbf{F}(\mathcal{M}, \textbf{s}; A)$ of all 01-fillings of a moon polyomino $\mathcal{M}$ with given column sum $\textbf{s}$ whose empty rows are $A$ and prove that this major index has the same distribution as the number of north-east chains,  which are a natural extension of inversions (resp. crossings) for permutations (resp. set partitions). Hence our result generalizes the classical equidistribution result for the permutation statistics inv and maj. I will present two proofs: an algebraic one using generating functions and a bijective one in the spirit of Foata's second fundamental transformation on words and permutations (this is joint work with William Chen, Catherine Yan, and Arthur Yang).

March registration (before March 25)

Fred Galvin - University of Kansas - intends to contribute a talk
 Tue, 3 Mar 2009 23:17:17  CombinaTexas Registration Form is submitted by Mr.  Fred Galvin  From: Mr.  Fred Galvin  E-Mail: galvin@math.ku.edu  From Position and Institution: faculty at the University of Kansas  Address Line 1: 3004 Oxford Road  Address Line 2: Lawrence, KS 66049  Address Line 3:  Contribute Talk: Yes  Talk Title: TBA  Abstract:
Catherine Yan - Texas A&M University
 Thu, 5 Mar 2009 11:38:49 CombinaTexas Registration Form is submitted by Dr.  Catherine Yan From: Dr.  Catherine Yan E-Mail: cyan@math.tamu.edu From Position and Institution: Professor at Texas A&M University Address Line 1: Department of Mathematics Address Line 2: Texas A&M University Address Line 3: College Station, TX 77843-3368 Contribute Talk: No Talk Title: Abstract:
Stanley Parkerson - University of Louisiana at Lafayette - intends to contribute a talk
 Sun, 8 Mar 2009 16:04:22 CombinaTexas Registration Form is submitted by Mr.  Stanley Parkerson  From: Mr.  Stanley Parkerson  E-Mail: andy_parkerson@yahoo.com  From Position and Institution: Instructor at University of Louisiana at Lafayette  Address Line 1: 1123 1/2 W Main St  Address Line 2: New Iberia, LA  Address Line 3: 70560  Contribute Talk: Yes  Talk Title: Antiautomorphisms on Directed Triple Systems  Abstract: A transitive triple $(a,b,c)$ is defined to be the set $\{(a,b),(b,c),(a,c)\}$ of ordered pairs. A directed triple system of order $v$, $DTS(v)$, is a pair $(V,\B)$, where $V$ is a set of $v$ points and $\B$ is a collection of transitive triples of pairwise distinct points of $V$ such that any ordered pair of distinct points of $V$ is contained in precisely one element of $\B$. A permutation of $V$ that maps $\B$ to itself is called an automorphism of $(V,\B)$. An antiautomorphism of $(V,\B)$ is a permutation of $V$ that maps $\B$ to $\B^{-1}$, where $\B^{-1}=\{(c,b,a)\mid(a,b,c)\in\B\}$. A permutation on a $DTS(v)$ is called $1$-bicyclic if the permutation consists of two cycles and one fixed point. Considered in this talk are necessary and sufficient conditions for the existence of a $DTS(v)$ admitting a $1$-bicyclic antiautomorphism with cycles of lengths $M$ and $N$.
Ernst L. Leiss - University of Houston - intends to contribute a talk
 Tue, 10 Mar 2009 17:07:53 CombinaTexas Registration Form is submitted by Dr.  Ernst L. Leiss  From: Dr.  Ernst L. Leiss  E-Mail: coscel@cs.uh.edu  From Position and Institution: Professor of Computer Science, University of Houston  Address Line 1: Department of Computer Science  Address Line 2: University of Houston  Address Line 3: Houston Texas 77204-3010  Contribute Talk: Yes  Talk Title: Some Comments on the Towers of Hanoi Problem  Abstract: A number of years ago (a quarter of a centuryâ¦), I took an interest in the Towers of Hanoi game. This is a problem that is frequently (ab)used in data structures and algorithms classes to illustrate the power of recursion. I subsequently generalized the game to be played on graphs; specifically, I assume a finite directed graph G=(V,E) with two distinguished nodes S and D, there are n disks of different sizes on node S such that no larger disk may lie on top of a smaller disk, and the objective is to move the n disks from S to D subject to the following rules: 1. Only one disk may be moved at a time and only along an edge in G. 2. A disk is always placed on top of all the disks on the node where it is moved and no larger disk may ever be placed on top of a smaller disk. If the problem can be solved for a given graph for all nâ¥1, I call this Hanoi problem solvable. It turned out that there is a rather elegant characterization of all those graphs with solvable Hanoi problems (Leiss). If for a given graph the associated Hanoi problem is not solvable, I call it a finite Hanoi problem. It is an interesting question how many disks can be moved in finite Hanoi problems. It turns out that there are graphs where sub-exponentially many disks can be moved (Leiss; Azriel and Berend). A related question is how many moves are required. While the original Hanoi problem (the complete graph on three nodes) requires 2n-1 moves, recent work (Azriel, Solomon and Solomon) indicates that significantly fewer moves may be required for some graphs with solvable Hanoi problems.
Eric Swartz - The Ohio State University - intends to contribute a talk
 Tue, 17 Mar 2009 13:35:31 CombinaTexas Registration Form is submitted by Mr.  Eric Swartz  From: Mr.  Eric Swartz  E-Mail: eswartz@math.ohio-state.edu  From Position and Institution: graduate student at The Ohio State University  Address Line 1: Department of Mathematics, The Ohio State University  Address Line 2: 231 West 18th Avenue  Address Line 3: Columbus, OH 43202  Contribute Talk: Yes  Talk Title: 2-ARC TRANSITIVE POLYGONAL GRAPHS OF LARGE GIRTH AND VALENCY  Abstract: A near-polygonal graph is a graph $\Gamma$ which has a set $\mathcal{C}$ of $m$-cycles for some positive integer $m$ such that each 2-path of $\Gamma$ is contained in exactly one cycle in $\mathcal{C}.$  If $m$ is the girth of $\Gamma$ then the graph is called polygonal.  Up until now, the only examples of 2-arc transitive polygonal graphs with arbitrarily large valency had girth no larger than seven, and the 2-arc transitive polygonal graph with largest girth had valency five and girth twenty-three (in fact, even with no restrictions on the automorphism group, there were no examples of polygonal graphs with odd girth greater than twenty-three).   We provide a construction of an infinite family of polygonal graphs of arbitrary girth $m$ with 2-arc transitive automorphism groups, showing that there are 2-arc transitive polygonal graphs of arbitrarily large valency for each girth $m$.
Doug Ray - Texas State University - intends to contribute a talk
 Thu, 19 Mar 2009 10:14:26 CombinaTexas Registration Form is submitted by Mr.  Doug Ray  From: Mr.  Doug Ray  E-Mail: dr36@txstate.edu  From Position and Institution: lecturer at Texas State University  Address Line 1: Department of Mathematics  Address Line 2: 601 University Drive  Address Line 3: San Marcos, Texas  78666  Contribute Talk: Yes  Talk Title: Cubic Cages  Abstract: Cages are graphs of specified regular degree and girth with the smallest possible order. A review of the current cubic cages will be given along with an algorithm for producing cages with a relatively small amount of information.
Lenore J. Cowen - Tufts University - intends to contribute a talk
 Thu, 19 Mar 2009 10:14:26 CombinaTexas Registration Form is submitted by Dr.  Lenore J. Cowen  From: Dr.  Lenore J. Cowen  E-Mail: cowen@cs.tufts.edu  From Position and Institution: faculty at Tufts University  Address Line 1: Department of Computer Science, Halligan Hall  Address Line 2: Tufts University  Address Line 3: Medford, MA 02155  Contribute Talk:  Talk Title: Fault Tolerance in Protein Interaction Networks: Stable Bipartite Subgraphs and Redundant Pathways  Abstract: As increasing amounts of high-throughput data for the yeast interactome becomes available, more system-wide properties are uncovered. One interesting question concerns the fault tolerance of protein interaction networks: whether there exist alternative pathways that can perform some required function if a gene essential to the main mechanism is defective, absent or suppressed. One signature pattern for redundant pathways is the BPM (between-pathway model) motif, first suggested by Kelley and Ideker. Past methods proposed to search for BPM motifs have had several important limitations. First, they have been driven heuristically by local greedy searches, which can lead to the inclusion of extra genes that may not belong in the motif; second, they have been validated solely by functional coherence of the putative pathways using GO enrichment, making it difficult to evaluate putative BPMs in the absence of already known biological annotation. We show how a simple "folk" theorem in graph theory (probably due to Erdos) can help us identify possible BPMs in such a way that not only do we get better coherence of biological function, but we also have a direct way to validate our results based directly on the structure of the network. We uncover some interesting biological examples of previously unknown putative redundant pathways in such areas as vesicle-mediated transport and DNA repair.
Li - Texas State University - intends to contribute a talk
 Sun, 22 Mar 2009 22:02:56 CombinaTexas Registration Form is submitted by Dr.  Li  From: Dr.  Li  E-Mail: liliangpan@yahoo.com.cn  From Position and Institution: Postdoctoral research associate at Texas State University  Address Line 1: Mathematics Department, Texas State University  Address Line 2: 601 University Drive  Address Line 3: San Marcos, TX 78666  Contribute Talk: Yes  Talk Title: On the Chung-Erdos inequality and the Borel-Cantelli lemma  Abstract: The Chung-Erdos inequality gives a lower bound on the amount of the union of finitely many finite sets if we know the amounts of all individual sets and all pairwise intersections. The Kochen-Stone inequality gives a lower bound on the probability of the upper limit of infinitely many events if we know the probabilities of all individual events and all pairwise intersections. In this talk, we generalize these two inequalities into weighted versions.
Daniela Ferrero - Texas State University - intends to contribute a talk
 Thu, 19 Mar 2009 10:14:26 CombinaTexas Registration Form is submitted by Dr.  Daniela Ferrero  From: Dr.  Daniela Ferrero  E-Mail: dferrero@txstate.edu  From Position and Institution: Faculty, Texas State University  Address Line 1: Department of Mathematics  Address Line 2: Texas State University  Address Line 3: San Marcos, TX 78666  Contribute Talk: Yes  Talk Title: Balance and Connectivity in Signed Graphs  Abstract: The sign of a cycle in a sign graph is defined as the product of the signs of its edges. A signed graph is locally balanced at a given vertex if all the cycles that contain it, are positive. A signed graph is balanced if it is balanced at every vertex, or equivalently, if all of its cycles have positive sign.  In this work we establish conditions for a signed graph to be balanced in terms of the connectivity of its underlying graph. Particularly, we prove that if the underlying graph is highly connected, local balance implies balance of the signed graph. These results are applied to some families of signed graphs whose underlying graphs are line graphs.
Roberto Barrera - Texas State University - intends to contribute a talk
 Mon, 23 Mar 2009 12:56:08  CombinaTexas Registration Form is submitted by Mr.  Roberto Barrera  From: Mr.  Roberto Barrera  E-Mail: rb1222@txstate.edu  From Position and Institution: student at Texas State University - San Marcos  Address Line 1: 7906 Lowdes Dr.  Address Line 2: Austin, TX 78745  Address Line 3:    Contribute Talk: Yes  Talk Title: Power Domination in Cylinders and Tori  Abstract: A crucial task for electric power companies consists of the continuous monitoring of their power network. This monitoring can be efficiently accomplished by placing phase measurement units (PMUs) at selected network locations. However, due to the high cost of the PMUs, their number must be minimized. The power domination problem consists of finding the minimum number of PMUs needed to monitor a given power network, as well as to determine the locations where they should be placed. In terms of graphs, the problem consists of finding minimal sets of vertices that dominate the entire graph according to some given propagation rules imposed by the nature of the power network. The power dominating problem is NP-complete. However, closed formulas for the power domination number of certain families of graphs, such as rectangular grids have been found. We extend the results for grids to other families of graph products: the cylinders Pn ÃCm for integers n > 1, m >2, and the tori Cn ÃCm for integers n,m >2. Joint work with D. Ferrero.
Brian K. Miceli - Trinity University
 Thu, 12 Mar 2009 11:29:53 CombinaTexas Registration Form is submitted by Dr.  Brian K. Miceli  From: Dr.  Brian K. Miceli  E-Mail: bmiceli@trinity.edu  From Position and Institution: Assistant Professor  Address Line 1: Mathematics Department  Address Line 2: One Trinity Place  Address Line 3: San Antonio, TX 78212  Contribute Talk: No  Talk Title:  Abstract:
Thomas Zaslavsky - Binghamton University (SUNY)
 Sun, 22 Mar 2009 14:27:15 CombinaTexas Registration Form is submitted by Mr.  Thomas Zaslavsky  From: Mr.  Thomas Zaslavsky  E-Mail: zaslav@math.binghamton.edu  From Position and Institution: Professor at Binghamton University (SUNY)  Address Line 1: Dept. of Mathematical Sciences  Address Line 2: Binghamton University (SUNY)  Address Line 3: Binghamton, NY 13902-6000  Contribute Talk:  Talk Title:  Abstract:
Neil Robertson - Ohio State University
 Mon, 23 Mar 2009 17:19:45  CombinaTexas Registration Form is submitted by Dr.  Neil Robertson  From: Dr.  Neil Robertson  E-Mail: robertso@math.ohio-state.edu  From Position and Institution: Emeritus Professor  Address Line 1: 6520 Wesley Way  Address Line 2: Westerville, Ohio 43082  Address Line 3:  Contribute Talk:  Talk Title:  Abstract:
Kiran B. Chilakamarri - Teaxs Southern University
 Mon, 23 Mar 2009 22:23:18  CombinaTexas Registration Form is submitted by Dr.  Kiran B. Chilakamarri  From: Dr.  Kiran B. Chilakamarri  E-Mail: Kchilakamarri@yahoo.com  From Position and Institution: Faculty at Teaxs Southern University  Address Line 1: 11022 Silkwood Drive, Houston, TX 77031  Address Line 2:  Address Line 3:  Contribute Talk: No  Talk Title:  Abstract:
Mahmud Akelbek - Texas State University - intends to contribute a talk
 Mon, 23 Mar 2009 22:57:44 CombinaTexas Registration Form is submitted by Dr.  Mahmud Akelbek  From: Dr.  Mahmud Akelbek  E-Mail: am44@txstate.edu  From Position and Institution: post-doc/lecturer at Texas State University   Address Line 1: Department of Mathematics  Address Line 2: Texas State University, 601 University Drive  Address Line 3: San Marcos, TX 78666, USA  Contribute Talk: Yes  Talk Title: A bound on the scrambling index of primitive digraph in terms of boolean rank  Abstract: The scrambling index of a primitive digraph $D$ is the smallest positive integer $k$ such that for every pair of vertices $u$ and $v$, there is a  vertex $w$ such that we can get to $w$ from $u$ and $v$ in $D$ by directed walks of length $k$; it is denoted  by $k(D)$. %The scrambling index of a primitive matrix $A$ can also defined as the smallest positive integer $k$ such that $A^k(A^t)^k=J$,    For an $m\times n$ boolean matrix $M$, its {\it boolean rank} $b(M)$ is the smallest positive integer $b$ such that for some $m \times b$ boolean matrix $A$ and $b\times n$ boolean matrix $B$, $M=AB$. The boolean rank of the zero matrix is defined to be zero. $M=AB$ is called a {\it boolean rank factorization} of $M$.  In this talk, we present an upper bound on the scrambling index of primitive digraph $D$ in terms of boolean rank $b(A)$ of its adjacency matrix $A(D)$.
Shanzhen Gao -Florida Atlantic University - intends to contribute a talk
 Tue, 24 Mar 2009 07:25:10 CombinaTexas Registration Form is submitted by Mr.  Shanzhen Gao  From: Mr.  Shanzhen Gao  E-Mail: sgao2@fau.edu  From Position and Institution: Ph.D. Student at Florida Atlantic Univeristy  Address Line 1: 260 nw 19th street, apt 5  Address Line 2: Boca Raton  Address Line 3: Florida 33432  Contribute Talk: Yes  Talk Title: Some results and problems on self-avoiding walks  Abstract: Some results and problems on self-avoiding walks Shanzhen Gao,  Shaun Sullivan,  Heinrich Niederhausen Florida Atlantic University A self-avoiding walk (SAW) is a sequence of moves on a lattice which does not visit the same point more than once. It was given as one of the two classical combinatorial problems in the Encylopaedia Britannica. A SAW is interesting for simulations because its properties cannot be calculated analytically. Calculating the number of self-avoiding walks in any given lattice is a common computational problem. We will present some interesting problems on SAWs and show you how to solve one problem.
Shaun Sullivan -Florida Atlantic University - intends to contribute a talk
 Tue, 24 Mar 2009 12:29:08 CombinaTexas Registration Form is submitted by Mr.  Shaun Sullivan From: Mr.  Shaun Sullivan E-Mail: ssulli21@fau.edu From Position and Institution: graduate student at Florida Atlantic University Address Line 1: 777 Glades Rd. Address Line 2: Boca Raton, FL 33431 Address Line 3: Contribute Talk: Yes Talk Title: Counting Strings in Ballot Paths Abstract: A ballot path stays weakly above the diagonal $y=x$, starts at the origin, and takes steps from the set $\{\uparrow ,\rightarrow \}=\{u,r\}$. A pattern is a finite string made from the same step set; it is also a path. We consider $b_{n,k}(m)$, the number of ballot paths containing a given pattern $k$ times reaching $(n,m)$. Certain types of patterns give sequences of polynomials that can be solved using multivariate Finite Operator Calculus. We only consider patterns $p$ such that its reverse pattern $\tilde{p}$ is a ballot path. We require this restriction so that the recurrence relation contains only values of the polynomial sequence that correspond to ballot paths and not the extensions of the polynomial sequence. For example, the pattern $p=uuurr$ would give the recurrence $b_{n,k}(m)=b_{n-1,k}(m)+b_{n,k}(m-1)-b_{n-2,k}(m-3)+b_{n-2,k-1}(m-3)$ when $m>n$ and $b_{n,k}(n)=b_{n-1,k}(n)$, so if we used the first recurrence to define the polynomials, we would be using values below the diagonal that do not correspond to ballot paths. Notice that $\tilde{p}=uurrr$ is not a ballot path. The patterns we consider here are called depth zero. To develop the recursions, we need to investigate the properties of the pattern we wish to avoid. Ballot paths reaching the diagonal can be viewed as Dyck paths, thus we are also counting strings in Dyck paths as a special case. Keywords: Pattern enumeration, ballot path, Dyck path, Finite Operator Calculus, Umbral Calculus
Adrian Heinz - Ball State University - intends to contribute a talk
 Tue, 24 Mar 2009 22:25:35  CombinaTexas Registration Form is submitted by Mr.  Adrian Heinz  From: Mr.  Adrian Heinz  E-Mail: hadriann@yahoo.com  From Position and Institution: Graduate student at Ball State University  Address Line 1: 2000 N Oakwood Ave. Apt 204  Address Line 2: Muncie, IN 47304  Address Line 3:  Contribute Talk: Yes  Talk Title:  Abstract:
Anthony Harrison - Texas State University - intends to contribute a talk
 Tue, 24 Mar 2009 22:39:15 CombinaTexas Registration Form is submitted by Mr.  Anthony Harrison  From: Mr.  Anthony Harrison  E-Mail: ah1411@txstate.edu  From Position and Institution: student at Texas State University  Address Line 1: 350 North St. #1218, San Marcos, TX 78666  Address Line 2:  Address Line 3:  Contribute Talk: Yes  Talk Title: L(2,1)-labeling of hypercubes  Abstract: The channel assignment problem consists of assigning frequencies to transmitters so that the spectrum of frequencies used is minimized, while the communications do not interfere. Two transmitters are considered to interfere with each other if they share similar frequencies and are at a prescribed distance from one another. The channel assignment problem translates into the following graph problem: find the minimum d such that the vertices of a given graph can be labeled with integers 0,1,â¦,d so that labels of vertices at a prescribed distance differ in a fixed amount. In particular, an L(2,1)-labeling of a graph prescribes that labels at adjacent vertices must differ by at least 2 and that labels for vertices at distance 2 must differ by at least 1. This problem was found to be NP-complete. We find L(2,1)-labelings for hypercubes that improve known upper bounds and show them to be minimal. Joint work with R. Barrera and D. Ferrero.
Kirsti Wash - Texas State University - intends to contribute a talk
 Wed, 25 Mar 2009 10:01:46 CombinaTexas Registration Form is submitted by Ms.  Kirsti Wash  From: Ms.  Kirsti Wash  E-Mail: kw1308@txstate.edu  From Position and Institution: graduate student Texas State University  Address Line 1: 601 University Dr.  Address Line 2: San Marcos, TX 78666  Address Line 3:  Contribute Talk: Yes  Talk Title: On The Bounds of The Domination Number of Permutation Graphs  Abstract: To follow
Valerie Hajdik - University of Houston - intends to contribute a talk
 Wed, 25 Mar 2009 11:37:52 CombinaTexas Registration Form is submitted by Ms.  Valerie Hajdik  From: Ms.  Valerie Hajdik  E-Mail: valerie.hajdik@gmail.com  From Position and Institution: incoming (fall) graduate student at University of Houston  Address Line 1: 3100 W 38th Ave  Address Line 2: Apt 8  Address Line 3: Denver, CO 80211  Contribute Talk: Yes  Talk Title: Experiences with "undergraduate" version of Graffiti.  Abstract: Graffiti is a computer program that makes conjectures in various sub-fields of mathematics and chemistry. Initial versions of Graffiti invented many conjectures that led to research publications - many by well-known mathematicians - and subsequent version of this program were used by students to learn graph theory "Texas style". I will discuss working on selected conjectures of Graffiti suitable for undergraduate students.
Jill Cochran - Texas State University at San Marcos - intends to contribute a talk
 Wed, 25 Mar 2009 14:06:07  CombinaTexas Registration Form is submitted by Ms.  Jill Cochran  From: Ms.  Jill Cochran  E-Mail: jc1781@txstate.edu  From Position and Institution: doctoral student at Texas State University at San Marcos  Address Line 1: 117 Lake Washington Dr.  Address Line 2:  Address Line 3:  Contribute Talk: Yes  Talk Title: Finding and Visualizing Networks of Terrorism Buried in Large Data Sets  Abstract:         The increasing availability of large amounts of information regarding terrorist activities and security of shipments amplifies the need for improved methods of analyzing and visualizing large data sets. We focus on the need to create accurate models to represent multidimensional data visually. These models are graphs, which represent networks of information derived from properties of the data or specifically related to geography or chronological sequences. Better visualization tools aid in preliminary data analysis. Then exploratory data analysis techniques such as clustering methods and graph theory techniques lead to better understandings of the data so that more informed decisions can be made in a timely manner. Tools have been developed to explore subnetworks or communities of interest by using clustering techniques related to minimum spanning trees and multidimensional scaling.
Ji Li - University of Arizona - intends to contribute a talk
 Wed, 25 Mar 2009 14:06:07  CombinaTexas Registration Form is submitted by Dr.  Ji Li  From: Dr.  Ji Li  E-Mail: jli@math.arizona.edu  From Position and Institution: postdoc at the University of Arizona  Address Line 1: 3033 E 6th Street  Address Line 2: G14  Address Line 3: Tucson, AZ85716  Contribute Talk: Yes  Talk Title: Fibonacci Compositions  Abstract: In Richard Stanleyâs Enumerative Combinatorics, Vol. 1, Exercise 14, page 46, we find several formulas expressing Fibonacci numbers in terms of sums over compositions. These formulas are easily proved using generating functions. Our goal is to study identities of this form systematically, and in particular, to answer the following questions: How can we find such identities? How can we prove them combinatorially? In this talk, I will provide some (probably incomplete) answers to the above questions. The work is mainly done by Professor Ira Gessel. This talk will be accessible to anybody who maintains a basic knowledge of generating functions.

March registration (after March 25)

Jian Shen - Texas State University
 Thu, 26 Mar 2009 22:52:05  CombinaTexas Registration Form is submitted by Dr.  Jian Shen  From: Dr.  Jian Shen  E-Mail: js48@txstate.edu  From Position and Institution: faculty at Texas State University  Address Line 1: 601 University Drive  Address Line 2: Department of Mathematics  Address Line 3: San Marcos, TX 78666  Contribute Talk: No  Talk Title:  Abstract:
Vikram Kamat - Arizona State University - intend to contribute a talk
 Sun, 29 Mar 2009 14:33:31 CombinaTexas Registration Form is submitted by Mr.  Vikram Kamat  From: Mr.  Vikram Kamat  E-Mail: vikram.kamat@asu.edu  From Position and Institution: Graduate Student at Arizona State University  Address Line 1: Department of Mathematics & Statistics  Address Line 2: Box 1804 Arizona State University  Address Line 3:  Tempe, AZ 85287    Contribute Talk: Yes  Talk Title: Erd\"os-Ko-Rado theorems for chordal graphs and trees  Abstract: One of the more recent generalizations of the Erd\"os-Ko-Rado theorem, formulated by Holroyd, Spencer and Talbot, defines the Erd\"os-Ko-Rado property for graphs in the following manner: for a graph G and a positive integer r, G is said to be r-EKR if no intersecting subfamily of the family of all independent vertex sets of size r is larger than the largest star, where a star centered at a vertex v is the family of all independent sets of size r containing v. In this talk, we present theorems which prove Erd\"os-Ko-Rado results for chordal graphs. We also consider the problem of finding maximum sized stars in trees. We conjecture that for any tree $T$, there is a maximum sized star centered at a leaf and prove this conjecture for $r\leq 4$. This is joint work with G. Hurlbert, Arizona State University.
Shelly Harvey - Rice University
 Sun, 29 Mar 2009 23:23:00  CombinaTexas Registration Form is submitted by Dr.  Shelly Harvey  From: Dr.  Shelly Harvey  E-Mail: shelly@rice.edu  From Position and Institution: Assistant Professor at Rice University  Address Line 1: Department of Mathematics, MS 136  Address Line 2: Rice University, P.O. Box 1892  Address Line 3: Houston, TX 77251-1892  Contribute Talk: No  Talk Title:  Abstract:
Siemion Fajtlowicz - University of Houston
 Mon, 6 Apr 2009 08:19:11 CombinaTexas Registration Form is submitted by   Siemion Fajtlowicz  From:   Siemion Fajtlowicz  E-Mail: math0@bayou.uh.edu  From Position and Institution: University of Houston, Professor  Address Line 1:  Address Line 2:  Address Line 3:  Contribute Talk: No  Talk Title:  Abstract:
Vladimir R. Rosenfeld - A&M University at Galveston
 Wed, 8 Apr 2009 15:50:12  CombinaTexas Registration Form is submitted by Dr.  Vladimir R. Rosenfeld  From: Dr.  Vladimir R. Rosenfeld  E-Mail: rosenfev@tamug.edu  From Position and Institution: postdoc at the A&M University at Galveston  Address Line 1:  Address Line 2:  Address Line 3:  Contribute Talk: Yes <=== CANCEL TALK  Talk Title: Monoids of Endomorphisms and Strong Endomorphisms of Graphs  Abstract: Let G be a finite graph with or without self-loops. A mapping of G to G is a graph endomorphism if it preserves adjacency (edges), and a strong graph endomorphism if, in addition, it also preserves nonedges. The monoids of all endomorphisms and of all strong endomorphisms of a graph G are denoted by EndG and SEndG, respectively. It is known that SEndG is always regular. Ulrich Knauer posed the following three questions: 1. Which regular monoids appear as SEndG for some graph G? 2. For which graphs G is EndG regular? 3. For which graphs is EndG = SEndG valid? We answer each of these questions.
Sosina Martirosyan Peterson - intend to contribute a talk
 Thu, 9 Apr 2009 09:23:22 CombinaTexas Registration Form is submitted by Dr.  Sosina Martirosyan Peterson  From: Dr.  Sosina Martirosyan Peterson  E-Mail: martsosi@yahoo.com  From Position and Institution: University of Houston -Clear Lake faculty  Address Line 1:  Address Line 2:  Address Line 3:  Contribute Talk: Yes  Talk Title: Perfect Hash Families  Abstract: A perfect hash family, PHF(N;k,v,t) is an N x k array with entries from a set of v symbols such that every Nxt  sub-array contains at least one row having distinct symbols. Perfect hash families have been studied intensively in the last two decades as they find numerous applications in computer sciences and cryptography. They are also useful tools in constructions of covering arrays and other designs. Combinatorial methods are used to provide explicit constructions of perfect hash families with improved parameters.  Several recursive constructions of perfect hash families are presented.
Art Duval - University of Texas at El Paso - intend to contribute a talk
 Thu, 9 Apr 2009 11:52:01 CombinaTexas Registration Form is submitted by Dr.  Art Duval  From: Dr.  Art Duval  E-Mail: artduval@math.utep.edu  From Position and Institution: faculty at University of Texas at El Paso  Address Line 1: University of Texas at El Paso  Address Line 2: Department of Mathematical Sciences  Address Line 3: El Paso, TX  79968-0514  Contribute Talk: Yes  Talk Title: Spanning trees and Laplacians of cubical complexes  Abstract: In previous work, we had extended the concept of a spanning tree from graphs to simplicial complexes; now we extend this idea further to CW-complexes, focusing especially on cubical complexes.  Once again, if a complex satsifies a mild technical condition, then its spanning trees can enumerated using its Laplacian matrices, generalizing the matrix-tree theorem.  We apply this to enumerate the spanning trees of cubes and of their complete skeleta, by first computing their Laplacian eigenvalues, which turn out to be integral.  We also define shifted cubical complexes, analogous to shifted simplicial complexes, and show that their Laplacian eigenvalues are integral as well. This is joint work with Croline Klivans and Jeremy Martin.
Ingeborg Matthews
 Mon, 13 Apr 2009 08:50:55 CombinaTexas Registration Form is submitted by Ms.  Ingeborg Matthews  From: Ms.  Ingeborg Matthews  E-Mail: Mingeborg@aol.com  From Position and Institution:  Address Line 1: 21311 Hannover Pines Dr.  Address Line 2: Spring, TX 77388  Address Line 3:  Contribute Talk: No  Talk Title:  Abstract:
Ermelinda DeLaVina - University of Houston (Downtown)
 Tue, 14 Apr 2009 09:23:22 CombinaTexas Registration Form is submitted by Dr.  Ermelinda DeLaVina From: Dr.  Ermelinda DeLaVina E-Mail: delavinae@uhd.edu From Position and Institution: faculty at the University of Houston - Downtown Address Line 1: CMS department S705 Address Line 2: University of Houston - Downtown Address Line 3: Houston, TX 77002 Contribute Talk: No Talk Title: Abstract:
Bill Waller - University of Houston (Downtown)
 Tue, 14 Apr 2009 10:39:32 CombinaTexas Registration Form is submitted by Dr.  Bill Waller From: Dr.  Bill Waller E-Mail: wallerw@uhd.edu From Position and Institution: faculty at University of Houston-Downtown Address Line 1: CMS Department Address Line 2: 1 Main St. Address Line 3: Houston TX 77002 Contribute Talk: No Talk Title: Abstract:
Ryan Pepper - University of Houston (Downtown)
 Tue, 14 Apr 2009 11:18:39 CombinaTexas Registration Form is submitted by Dr.  Ryan Pepper From: Dr.  Ryan Pepper E-Mail: pepperr@uhd.edu From Position and Institution: Faculty at UH-D Address Line 1: University of Houston -- Downtown Address Line 2: One Main Street Address Line 3: Houston, TX 77002 Contribute Talk: No Talk Title: Abstract:
Jay Bagga - Ball State University - intend to contribute a talk
 Wed, 15 Apr 2009 14:04:10 CombinaTexas Registration Form is submitted by Dr.  Jay Bagga  From: Dr.  Jay Bagga  E-Mail: jbagga@bsu.edu  From Position and Institution: Professor, Ball State University  Address Line 1:  Address Line 2:  Address Line 3:  Contribute Talk: Yes  Talk Title:  Abstract:
Martin Malandro - Sam Houston State University
 Wed, 15 Apr 2009 11:58:23 CombinaTexas Registration Form is submitted by Dr.  Martin Malandro  From: Dr.  Martin Malandro  E-Mail: malandro@shsu.edu  From Position and Institution: Assistant Professor at Sam Houston State University  Address Line 1:  Address Line 2:  Address Line 3: :  Contribute Talk: No  Talk Title:  Abstract:
Xingde Jia - Texas State University
 Wed, 15 Apr 2009 17:02:47 CombinaTexas Registration Form is submitted by Dr.  Xingde Jia  From: Dr.  Xingde Jia  E-Mail: jia@txstate.edu  From Position and Institution: Professor at Texas State University  Address Line 1: 601 University Drive  Address Line 2: San Marcos, Texas 78666  Address Line 3:  Contribute Talk: No  Talk Title:  Abstract:
Laura Felicia Matusevich - Texas A&M
 Thu, 16 Apr 2009 00:12:57 CombinaTexas Registration Form is submitted by Dr.  Laura Felicia Matusevich  From: Dr.  Laura Felicia Matusevich  E-Mail: laura@math.tamu.edu  From Position and Institution: faculty at Texas A&M  Address Line 1: Dept. of Mathematics, Texas A&M University  Address Line 2: Mailstop 3368  Address Line 3: College Station, TX 77843-3368  Contribute Talk:  Talk Title:  Abstract:
Frank Sottile - Texas A&M
 Fri, 17 Apr 2009 14:53:11 CombinaTexas Registration Form is submitted by Dr.  Frank Sottile  From: Dr.  Frank Sottile  E-Mail: sottile@math.tamu.edu  From Position and Institution: Professor at Texas A&M University  Address Line 1:  Address Line 2:  Address Line 3:  Contribute Talk: No  Talk Title:  Abstract:
Nathaniel Dean - Texas State University
 Fri, 17 Apr 2009 20:28:32 CombinaTexas Registration Form is submitted by Dr.  Nathaniel Dean  From: Dr.  Nathaniel Dean  E-Mail: nd17@txstate.edu  From Position and Institution: Professor at Texas State University  Address Line 1: Department of Mathematics  Address Line 2: 601 University Drive  Address Line 3: San Marcos, TX 78666  Contribute Talk: No  Talk Title:  Abstract:
Aaron Lauve - Texas A&M
 Fri, 17 Apr 2009 21:10:24 CombinaTexas Registration Form is submitted by Dr.  Aaron Lauve  From: Dr.  Aaron Lauve  E-Mail: lauve@math.tamu.edu  From Position and Institution: Visiting Professor at Texas A&M University  Address Line 1: 1525 E 29th ST, #610  Address Line 2: Bryan, TX  77802  Address Line 3:  Contribute Talk: No  Talk Title:  Abstract:
Jing Ma - Rice University
 Fri, 24 Apr 2009 23:47:22 CombinaTexas Registration Form is submitted by Ms.  Jing Ma  From: Ms.  Jing Ma  E-Mail: jm11.rice@gmail.com  From Position and Institution: PH.D student of Rice University  Address Line 1: 1515 Bissonnet St. Unit 208  Address Line 2: Houston, Texas, 77005  Address Line 3:  Request for Support: No  Comment on support:  Contribute Talk: No  Talk Title:  Abstract:

Current Address: Department of Mathematics, PGH Building, University of Houston, Houston, Texas 77204-3008
Phone: (713) 743-3500 - Fax: (713) 743-3505