# The Combinatorics Group: Seminars

Every week or two during the Fall and Winter semesters we have a Combinatorics Seminar. Refreshments are frequently provided.

Speakers and topics for the present semester (and recent semesters) are shown below.

Presentations listed in italics were given as Colloquia.

| ||

Date | Speaker | Topic |

Friday, 2 November | Gena Hahn, Universite de Montreal | Cops and robbers on graphs - finite and infinite |

## | ||

Date | Speaker | Topic |

Friday, 29 June | Daniel Horsley, Monash University | Compressed sensing and hash families |

Winter 2012 | ||

Date | Speaker | Topic |

Wednesday, 14 March | Ryan Tifenbach, Memorial University of Newfoundland | Spectral graph theory I |

Wednesday, 21 March | Rebecca Milley, Dalhousie University | Lessons in Losing: An Introduction to Misere Game Theory |

Wednesday, 28 March | Ryan Tifenbach, Memorial University of Newfoundland | Spectral graph theory II |

Winter 2011 | ||

Date | Speaker | Topic |

Wednesday, 23 March | Jared Howell, Memorial University of Newfoundland | The Intersection of Latin Squares |

Summer 2010 | ||

Date | Speaker | Topic |

Tuesday, 31 August | Colin Reid, McMaster University | T-chromatic index for Steiner S(2; k; v)s |

| ||

| Speaker | Topic |

Monday, 15 February | Robert Bailey, University of Regina | Hamiltonian decompositions of hypergraphs |

Friday, 26 February | Andrea Burgess, Memorial University of Newfoundland | Cycle decompositions of some families of graphs |

Friday, 05 March | Daniel Horsley, Memorial University of Newfoundland | Nimber Theory: Impartial Combinatorial Games - I |

Friday, 12 March | Daniel Horsley, Memorial University of Newfoundland | Nimber Theory: Impartial Combinatorial Games - II |

Friday, 09 April | Robert Gallant, Sir Wilfred Grenfell College | Finding discrete logarithms using additional information |

| ||

| Speaker | Topic |

Thursday, 08 October | Dariusz Dereniowski, Gdansk University of Technology | Nonclassical measures for evaluating search strategies |

Thursday, 15 October | Daniel Horsley, Memorial University of Newfoundland | Embedding partial Steiner triple systems |

Thursday, 22 October | Asiyeh Sanaei, Memorial University of Newfoundland | Rectilinear Symmetric Crossing Number of Complete Graphs |

Thursday, 05 November | J.C. Loredo-Osti, Memorial University of Newfoundland | Trees of descent, Steiner trees and the computation of likelihood in complex genealogies |

Thursday, 03 December | Andrew Jesso, Memorial University of Newfoundland | The Hamiltonicity of Block-Intersection Graphs of Balanced Incomplete Block Designs |

Friday, 11 December | Rebecca Keeping, Memorial University of Newfoundland | The Watchman's Walk Problem and its Variations |

| ||

| Speaker | Topic |

Friday, 31 July | Adrian Vetta, McGill University | Paths, viruses, and galaxy cutsets |

| ||

| Speaker | Topic |

Friday, February 13th | Oznur Yasar Diner, Memorial University of Newfoundland | Forbidden Minor Constructions for 4-Searchable Series-Parallel Graphs |

Friday, February 20th | David Pike, Memorial University of Newfoundland | Phylogenetic Networks for Human mtDNA Haplogroup T |

Friday, February 27th | Danny Dyer, Memorial University of Newfoundland | Cyclic perfect $T(P_2 cup P_2 cup P_2)$ triple systems |

Friday, March 13th | Nabil Shalaby, Memorial University of Newfoundland | Skolem-Langford Type Sequences |

Friday, March 20th | Ahmed Ababheh, Memorial University of Newfoundland | Disjoint starter sequences |

Tuesday, April 28th | Rebecca Keeping, Memorial University of Newfoundland | The Watchman's Walk Problem with Time Restraints |

| ||

| Speaker | Topic |

| Dominique de Werra,École Polytechnique Fédérale de Lausanne | Graph transformations and peseudoboolean reduction |

Thursday, | David Pike, Memorial University of Newfoundland | Hamiltonicity and Restricted Block-Intersection Graphs of t-Designs |

Thursday, | Dariusz Dereniowski, Gdansk University of Technology | Using edge rankings for searching in partial orders |

Thursday, | Daniel Horsley, Memorial University of Newfoundland | A solution to Alspach's problem for complete graphs of large odd order |

Thursday, | Edgar Goodaire, Memorial University of Newfoundland | Group-based Latin Squares |

Thursday, | Rebecca Keeping, Memorial University of Newfoundland | Maximum k-Limited Packings in Trees |

Thursday, | Danny Dyer, Memorial University of Newfoundland | Two coloured path decompositions |

Tuesday, | Rebecca Keeping, Memorial University of Newfoundland | A Review of the Watchman's Walk Problem |

| ||

| Speaker | Topic |

| Vaclav Linek,University of Winnipeg | Octahedral Designs |

| Nancy Clarke,Acadia University | Variations of the Cops and Robber Game Played with Imperfect Information |

| Boting Yang,University of Regina | Edge Searching on Cycle-Disjoint Graphs |

Wednesday, | Pawel Pralat, Dalhousie University | Cleaning d-regular graphs with brushes |

| ||

Date | Speaker | Topic |

Wednesday, Feb 13th | Daniela Silvesan, Memorial University | The spectrum of Skolem and hooked Skolem sequences with prescribed pairs in common |

Friday, Feb 29th | Oznur Yasar Memorial University | Fast Search is Linear for Trees |

Wednesday, May 7th | Laura Chavez-Lomeli, Simon Fraser University | Chromatic and flow number for matroids |

| ||

Date | Speaker | Topic |

Friday,Jan 26th | Vaclav Linek,University of Winnipeg | Langford sequences: parametrizations, commutative diagrams and quotients |

| ||

Date | Speaker | Topic |

Tuesday, Oct 31st | Josh Manzer Memorial University | Skolem labeling of generalized windmill graphs |

| ||

Date | Speaker | Topic |

Thursday,May 11 | Brian Alspach,University of Regina | Groups acting on graphs |

Thursday, Jun 15 | Gary MacGillivray, University of Victoria | Circular colourings of hypergraphs |

Tuesday, Aug 8 (Japan) | Shinya Fujita, Gunma National College of Technology | Recent results on vertex-disjoint cycles in graphs |

Tuesday, Aug 15 | Shinya Fujita, Gunma National College of Technology (Japan) | Non-separating subgraphs in highly connected graphs |

| ||

Date | Speaker | Topic |

Thursday, Feb 16 | Sueng-Byond (Light) Go, Memorial University | Cyclic Steiner triple systems with cyclic subsystems |

Thursday, Mar 2 | Yubo Zou, Memorial University | Dominating hypercubes |

Thursday, Apr 6 | Brenda Wicks, Memorial University | Graceful labelings of triangular cacti graphs |

Thursday, Apr 20 | Oznur Yasar, Memorial University | Edge searching weighted graphs |

| ||

Date | Speaker | Topic |

Friday, Nov 18 | Colin Reid, Memorial University | Near-lambda-fold Skolem sequences and infinite Skolem sequences |

Friday, Nov 25 | Yubo Zou, Memorial University Decycling | Fibonacci cubes |

| ||

Date | Speaker | Topic |

Thursday, Jun 30 | Danny Dyer, University of Regina | Isomorphic factorizations of circulant graphs |

| ||

Date | Speaker | Topic |

Friday, Feb 25 | Oliver Ittig, Swiss Federal Institute of Technology | Scheduling with multiprocessors: A rounding network algorithm with a constant error |

| ||

Date | Speaker | Topic |

Tuesday, Nov 2 | Nabil Shalaby, Memorial University | Skolem-type rectangles |

Tuesday, Nov 9 | Yubo Zou, Memorial University | Decycling of Cartesian product of cycles |

Tuesday, Nov 16 | David Morgan, University of Alberta | Useful vertex names: Informative labelling schemes for graphs |

Tuesday, Nov 23 | Andrea Burgess, Memorial University | Invariants for even cycle systems |

Tuesday, Nov 30 | Colin Reid, Memorial University | The existence of looped m-near-Skolem sequences |

| ||

Date | Speaker | Topic |

Friday, Jun 18 | Danny Dyer, Simon Fraser University | Using cliques to sweep graphs |

| ||

Date | Speaker | Topic |

Thursday, Oct 16 | Eddie Cheng, Oakland University | An introduction to linear integer programming via the stable set problem |

| ||

Date | Speaker | Topic |

Wednesday, Jul 2 | Danny Dyer, Simon Fraser University | Two-coloured path decompositions |

| ||

Date | Speaker | Topic |

Tuesday, Feb 4 | Rolf Rees, Memorial University | Constructing Steiner triple systems for all admissible orders - Part I |

Tuesday, Feb 18 | Rolf Rees, Memorial University | Constructing Steiner triple systems for all admissible orders - Part II |

Tuesday, Mar 25 | Nabil Shalaby, Memorial University | Skolem-type sequences |

Tuesday, Apr 1 | Rolf Rees, Memorial University | Constructing Steiner triple systems for all admissible orders - Part III |

| ||

Date | Speaker | Topic |

Friday,Aug 9 | Martin Grüttmüller,University of Rostock (Germany) | Completing partial Latin squares with prescribed diagonals |

Wednesday,Aug 14 | Gennian Ge,Suzhou University (P.R. China) | Whist tournaments |

| ||

Date | Speaker | Topic |

Wednesday, Jan 30 | Eric Moorhouse, University of Wyoming | Projective planes - Part I |

Wednesday, Feb 6 | Eric Moorhouse, University of Wyoming | Projective planes - Part II |

Wednesday, Feb 20 | Nabil Shalaby, Memorial University Disjoint | Skolem sequences |

Wednesday, Mar 6 | Rolf Rees, Memorial University | Embedding cyclic partial Steiner triple systems |

Wednesday, Mar 27 | Patrick Fleming, University of Wyoming | Generating functions |

Wednesday, Apr 3 | Alasdair Graham, Memorial University | A survey of packings and coverings of simple graphs |

Wednesday, Apr 3 | Aygul Mamut, Memorial University and Xinjiang University | Decompositions of graphs into 1-factors |

Thursday, Apr 4 | Chao Zhong, Memorial University | Perfect graphs |

| ||

Date | Speaker | Topic |

Monday, Sep 10 | Sarah Mathews, Memorial University | Configurations in Steiner triple systems |

Wednesday, Sep 19 | Rolf Rees, Memorial University | On holes in t-designs - Part I |

Thursday,Sep 27 | Vaclav Linek,University of Winnipeg | Pattern avoidance: The Abelian case |

Wednesday, Oct 3 | Rolf Rees, Memorial University | On holes in t-designs - Part II |

Wednesday, Oct 17 | Alasdair Graham, Memorial University | Skolem labelled graphs |

Wednesday, Oct 31 | Eric Moorhouse, University of Wyoming | The transfer matrix method |

Wednesday,Nov 21 | Eddie Cheng,Oakland University | Submodular functions, polymatroids and strength |

Friday,Nov 30 | Joanna Ellis-Monaghan,University of Vermont | An introduction to the Tutte polynomial |

| ||

Date | Speaker | Topic |

Tuesday, Feb 6 | Nabil Shalaby, Memorial University | Skolem labelled graphs |

Tuesday, Feb 13 | Michael Parmenter, Memorial University | Applications of graph theory to the study of DNA and RNA chains (1) |

Tuesday, Feb 20 | Michael Parmenter, Memorial University | Applications of graph theory to the study of DNA and RNA chains (2) |

Tuesday, Mar 13 | Rolf Rees, Memorial University | A survey of Kirkman designs (2) |

Tuesday, Mar 20 | David Morgan, Memorial University | Domination in graphs (1) |

Tuesday, Mar 27 | A.E. Fekete, Memorial University | Spectral sequences of integers |

Tuesday, Apr 10 | David Pike, Memorial University | A cryptographic application of graph theory |

Tuesday, Apr 17 | David Morgan, Memorial University | Domination in graphs (2) |

Tuesday, Apr 24 | David Morgan, Memorial University | Gracefully labelled trees from Skolem and related sequences |

Wednesday,Apr 25 | Alex Rosa,McMaster University | Large sets of Steiner triple systems |

| ||

Date | Speaker | Topic |

Tuesday, Sep 19 | Eugene Lilly, Memorial University | Mutually orthogonal Latin squares |

Tuesday, Sep 26 | Sarah Mathews, Memorial University | Cyclically indecomposable two-fold triple systems from Skolem sequences |

Tuesday, Oct 3 | Robin Swain, Memorial University | 8-cycle decompositions of the Cartesian product of two complete graphs |

Tuesday, Oct 10 | Vesselin Dresnky, Bulgarian Academy of Sciences | Applications of the pigeon hole principle |

Tuesday, Oct 17 | Rolf Rees, Memorial University | A survey of Kirkman designs (1) |

Tuesday, Oct 24 | David Morgan, Memorial University | A survey of graceful labelings |

| ||

Date | Speaker | Topic |

Thursday, Feb 17 | Michael Parmenter, Memorial University | On groups with redundancy in multiplication |

Thursday, Mar 2 | Rolf Rees, Memorial University | Magic labelings of graphs |

| ||

Date | Speaker | Topic |

Thursday, Nov 4 | Nabil Shalaby, Memorial University | Optimal complementary coverings of the complete graphs by paths of length three |

Thursday, Nov 23 | Yuri Bahturin, Memorial University, and Victor Petrogradsky, Ul'yanovsk State University (Russia) | Young diagrams, generating functions and proper identities II |

Thursday, Dec 2 | David Morgan, Memorial University | Applications of Polya's counting theorem in chemical compounds |

| ||

Date | Speaker | Topic |

Thursday, Jan 26 | Nabil Shalaby, Memorial University | Skolem sequences and applications - I |

Tuesday, Feb 2 | Nabil Shalaby, Memorial University | Skolem sequences and applications - II |

Tuesday, Feb 9 | David Pike, Memorial University | Perfect 1-factorisations - I |

Tuesday, Feb 16 | David Pike, Memorial University | Perfect 1-factorisations - II |

Tuesday, Mar 2 | David Morgan, Memorial University | Graceful labelings of graphs - II |

| ||

Date | Speaker | Topic |

Tuesday, Sep 29 | Tara Stuckless, Memorial University | The existence of looped Langford sequences |

Tuesday, Oct 6 | David Pike, Memorial University | Decomposing block-intersection graphs of Steiner triple systems into triangles - I |

Tuesday, Oct 20 | David Pike, Memorial University | Decomposing block-intersection graphs of Steiner triple systems into triangles - II |

Tuesday, Oct 27 | Antal Fekete, Memorial University | Step-numbers and their applications - I |

Tuesday, Nov 3 | Antal Fekete, Memorial University | Step-numbers and their applications - II |

Tuesday, Nov 10 | Antal Fekete, Memorial University | Step-numbers and their applications - III |

Tuesday, Nov 17 | Antal Fekete, Memorial University | Step-numbers and their applications - IV |

Tuesday, Nov 24 | David Morgan, Memorial University | Graceful labelings of graphs - I |