# Seminars

List of previous talks at the Graduate Colloquium:

Talks presented by students are marked by *.

### 2015-2016

 May 27 Natasha Dobrinen An almost topological Ramsey space of strong triangle-free trees and applications to the universal triangle-free graph May 20 Mathai Varghese (University of Adelaide) Atiyah-Singer index theory, fractional variant and applications May 13 Drew Ash* My 7-Year Journey to Temporary Employment May 6 Drew Ash* Topological speedups (PhD defense) Apr 29 Stan Gudder Discrete Scalar Quantum Field Theory Apr 22 Kirk Boyer* Combinatorics and Geometry in Ray Sensor Networks Apr 15 Wesley Fussner* and Allegra Reiber Adventures in Inquiry and Self-Regulated Learning Apr 1 Nishant Chandgotia (Brown University) Distance between walks on graphs Feb 18 Thomas French* Follower, Predecessor, and Extender Set Sequences of One-Dimensional Shifts Jan 22 Geraldo de Souza (Auburn University) Lipschitz Spaces, Generalized Lipschitz Spaces, and their importance in analysis Jan 15 Paul Horn Designing designs: Keevash's proof of the Existence Conjecture Nov 13 Aysel Erey Counting restrained colorings of graphs Nov 6 Dan Hathaway Introduction to cardinal characteristics Oct 30 Sergio Lopez-Permouth (Ohio University) Algebras having bases that consist solely of units Oct 23 Stephen Hartke (CU Denver) Computational Combinatorics: Uniquely K_r-saturated Graphs Oct 9 Ana Mamatelashvili (Auburn University) Tukey ordering and subsets of ω1 Oct 2 Diane Ojeda (University of Toronto) Structural Ramsey Theory Sep 25 Math faculty Advice to grad students: Building your portfolio and finding a job

### 2014-2015

 May 29 Ghodratollah Aalipour (Kharazmi University, Iran) Laplacian eigenvalues of graphs and simplicial complexes May 22 Riquelmi Cardona* The Finite Embeddability Property for some Noncommutative knotted varieties of RL and DRL May 15 Ed Bueler (University of Alaska, Fairbanks) Mathematical tools and obstacles in models of ice sheets May 8 Mark Greer (University of North Alabama) Moufang semidirect products of loops with groups and inverse property extensions May 1 Phil DeOrsey* (CU Denver) A Classification of Hyperfocused 12-arcs Apr 24 Lauren Irby* A Quick Look at Women in Mathematics Apr 17 Jeff Boersema (Seattle University) Real C*-algebras and real structures in graph C*-algebras Apr 3 Michael Kinyon Automated Deduction and Algebra Mar 27 Allegra Reiber Metacognition, Collaboration, and Inquiry to support self-enabled learning in mathematics Mar 6 Nate Eldredge (University of Northern Colorado) Geometry and probability on sub-Riemannian manifolds: taking the scenic route Feb 27 Ronnie Pavlov An introduction to the theory of percolation Feb 13 Paul Horn One day in May Feb 6 Stan Gudder The Universe According to Gudder Jan 30 Konrad Aguilar* Twisted SU(2) and Noncommutative Metric Geometry Jan 23 Lori Alvin Low Dimensional Dynamics: Unimodal Maps and the Quest for Homeomorphisms Nov 14 Mei Yin A gentle introduction to exponential random graphs Nov 7 Adam Purcilly* Disjunctive Rado Numbers for Two Equations of Different Forms Oct 31 Natasha Dobrinen Rainbow Ramsey theorems for bounded colorings of finite subgraphs of the Rado graph Oct 24 Florian Pfender (CU Denver) Semidefinite programming in extremal graph theory Oct 17 Drew Ash* Topological Speedups Oct 10 Kate Pearce* Where Are All the Women in Mathematics?: A Survey of History's Most Influential Women Mathematicians Sep 26 Stan Gudder Simple Problems, Surprising Solutions

### 2013-2014

 May 30 Gabor Lippner (Harvard University) Measurable graph theory May 23 Sheila Miller (New York City College of Technology) Critical sequences of rank-to-rank embeddings and a tower of finite left distributive algebras May 16 Gavin St. John *Goedel's theorems May 9 Timothy Trujillo *Thesis Defense: Topological Ramsey spaces, associated ultrafilters, and their applications to the Tukey theory of ultrafilters and Dedekind cuts of nonstandard arithmetic May 2 Stan Gudder The Universe According to Gudder Apr 25 Andy Linshaw The chiral de Rham complex Apr 18 Gabriel Giron *Tsirelson Type Spaces Apr 11 Lauren Morey *Integral enumeration formulas Apr 4 Natasha Dobrinen Introductory overview of the Tukey theory of ultrafilters Feb 28 Drew Ash *D-Simplices of Minimal Cantor Systems Feb 21 Nathan McNew *Things you can prove with a degree from DU, two results in number theory Feb 14 Tim Trujillo *Ramsey for R1 Ultrafilters and Their Dedekind Cuts: II Feb 7 Florian Sobieczky The Newsboy Problem Jan 31 Riqulemi Cardona *The Finite Embeddability Property for Noncommutative Knotted Extensions of RL Jan 24 George Herrmann *Lipschitz Seminorms toward Quantum Metric Spaces Nov 8 Alvaro Arias The Ramsey Theorem in Banach Spaces Oct 18 Paul Horn Probabilistic combinatorics and spectral graph theory: (not so) strange bedfellows Oct 11 Thomas French *Sequences of Minimal Complexity Oct 4 Adriana Suarez Provable Security for Key Establishment Protocols Sep 27 Lori Alvin Adding machines and Low Dimensional Dynamics Sep 20 Jose Mijares On topological Ramsey spaces

### 2012-2013

 May 17 Timothy Trujillo * Diamonds as initial structures in the Tukey hierarchy of p-points May 10 Mark Greer * PhD Defense, Loops and their permutation groups Apr 26 Rick Kitchen Interactive assessment of teaching and learning Apr 12 Andreas Blass (Michigan) Abelian groups that want to be free Mar 29 Jonathan D. H. Smith (Iowa State) Beyond groups Mar 8 Frank Schroeck The axioms of quantum mechanics Nov 9 Stan Gudder Probability problems Nov 2 Tim Trujillo * Higher Dimensional Ramsey Theory Oct 26 Florian Sobieczky The blind ant and the myopic ant in the labyrinth Oct 19 Alvaro Arias Operator algebras Oct 12 Ronnie Pavlov Undecidability and computability in symbolic dynamics Oct 5 Zhe Liu An introduction to operator algebras, unbounded operators, and their relations to physics Sep 21 Dennis Pace * Axiom of Choice: Equivalences and Applications

### 2011-2012

 May 17 Christian Westhof * The Arrival of the Truth Table May 4 David Ellerman (University of California at Riverside) Interpreting Quantum Mechanics: The Objective Indistinctness Vision of Quantum Reality Based on the Logic of Partitions Apr 27 Mark Greer * Sylow Theory for Commutative Automorphic Loops Apr 20 Drew Ash * Ergodic and Weak-Mixing Transformations Apr 13 Jimmy Thorne * A better integral Apr 6 Rick Ball Truncated vector lattices Mar 9 Timothy Trujillo * The Topological Ramsey Space H^2 Mar 2 George Herrmann * Sequence, Nets and Moore-Smith Convergence Feb 10 Thomas French * Spatial Voting Theory as a Predictive Model for Elections Jan 20 Natasha Dobrinen The Ellentuck space and Ramsey ultrafilters Nov 11 Drew Ash * A word on Sarkovskii's Theorem Nov 4 Timothy Trujillo * Ultraproducts and Nonstandard Models of Arithmetic Oct 28 Stan Gudder Quantum probability theory Oct 21 Alvaro Arias Continuous and non-continuous linear maps in norm spaces and Banach spaces Sep 30 Jerry Lodder (New Mexico State) Teaching Mathematics from Historical Sources Sep 23 Sean Cox (Muenster, Germany) The Tree Property and elementary embeddings Sep 16 Natasha Dobrinen Some notions in set theory

### 2010-2011

 May 20 Yaodong Xiang * An introduction to Black-Scholes equation May 6 Jeff Farmer Why math is real: Three short stories Apr 29 Kyle Pula * Approximate transversals of latin squares (PhD defense) Apr 22 Mark Greer * Some varities of dissociative loops - structures and constructions Apr 15 Nawal Alznad * T-uniformly continuous functions on a flow Apr 1 Frederic Latremoliere Irreducible covariant representations of automorphic actions of finite groups on C *-algebras Mar 25 Gabriel Giron-Garnica * Dynkin pi-lambda theorem Mar 11 Andrew Linshaw (Darmstadt Technical University, Germany) Introduction to vertex algebras and some connections with classical invariant theory Feb 11 Jan Mycielski (CU Boulder) Set theory and Learning theory Feb 4 Natasha Dobrinen An overview of set theory Jan 28 Nic Ormes Self-inducing minimal Cantor systems Jan 21 Petr Vojtechovsky A mathematical result is born! Nov 14 Timothy Trujillo * Ultrafilter mappings and their Dedekind cuts Nov 5 Nichole Carlson (University of Colorado Denver) Opportunities in biostatistics Oct 29 Jeff Farmer Where counting comes from: Developments in research on early mathematics learning Oct 22 Michael Kinyon A gentle introduction to nonassociativity Oct 15 Bart Kastermans (University of Colorado Boulder) (Maximal) Cofinitary Groups Oct 8 Ronnie Pavlov Shifts of finite type and entropy in one and two dimensions Oct 1 Kyle Pula * Large partial transversals of small latin squares Sep 24 Daniel Van Der Vieren The Rubik's cube as a Vigenere-transposition cryptosystem Sep 17 Natasha Dobrinen Introduction to Ramsey theory

### 2009-2010

 May 27 Sheila Miller (US Military Academy, West Point) Free left distributive algebras May 14 Nathan McNew * Efficient realization of nonzero spectra by polynomial matrices May 7 Brett Werner * Strong orbit equivalence and residuality Apr 30 Riquelmi Cardona Fuentes * On widest empty Apr 23 Stan Gudder Quantum probability theory Apr 16 Rick Ball Reflections on reflections Apr 9 Jim Hagler Bases in Banach spaces Apr 2 Nic Ormes The conjugacy problem for shifts of finite type Mar 5 Petr Vojtechovsky Graphs with large girth and chromatic number Feb 19 Man-Duen Choi (University of Toronto) Non-commutative magic everywhere Feb 15 Andrzej Dudek (Carnegie Mellon University) On generalized Ramsey numbers of Erdos-Rogers and Folkman Feb 12 Marius Ionescu (University of Connecticut) Entropy calculations in fractal dynamical systems Feb 8 Ronnie Pavlov (University of British Columbia) Shifts of finite type and entropy in one and two dimensions Feb 5 Greg Oman (Ohio University) Jonsson modules Jan 29 Alvaro Arias Commutant lifting theorem Jan 22 Ales Drapal (Charles University in Prague, Czech Republic) Quadratic sieve Nov 13 Frederic Latremoliere Compact quantum metric spaces Nov 6 Timothy Trujillo * Ultrafilters on $\omega$ Oct 30 Michael Kinyon Loops and 3-nets Oct 23 Annette Locke * Thesis defense Oct 16 Alexander Kechris (California Institute of Technology) The complexity of classification problems in ergodic theory Oct 9 Clifton E. Ealy, Jr. (Western Michigan University) On profinite loops Oct 2 Ales Drapal (Charles University in Prague, Czech Republic) Cryptography: The mathematics and the curriculum Sep 25 Natasha Dobrinen Boolean algebras Sep 18 Katherine Thompson (University of Vienna, Austria) Simple axioms, a labyrinth of universes

### 2008-2009

 Oct 24-31 Paul Truman Hopf Algebras In Galois Module Theory Oct 17 Tim Trujillo * Attractors for Nonlinear Reaction-Diffusion Equations in Unbounded Domains Oct 9 Allegra Reiber K-theory of categories and Bivariant theories II Oct 2 Allegra Reiber K-theory of categories and Bivariant theories I Sep 26 Kyle Pula * Transversals and their generalizations in Latin squares Sep 19 Dan Daly * Reduced decompositions, repetitions, and permutation patterns

### 2007-2008

 May 30 Nic Ormes Continued fractions May 23 Annette Locke * The Banach space HT and its characteristics May 16 Jonathan Von Stroh * Dilations, compressions, and the von Neumann inequality May 9 Dan Daly * Reduced decompositions with few repetitions and permutation patterns May 2 Yan Mayster * Minimax approximation of 2D points using step functions Apr 25 Sarah Bailey Frick (Ohio State) Ergodic invariant measures and Limited Scope adic transformations Apr 18 Kyle Pula * Generalizing the Hall-Paige conjecture Apr 11 Rick Ball Introduction to pointfree topology Apr 4 Watching the movie "Hakase No Aishita Suushiki" ("The Professor and His Beloved Equation") Mar 7 Mark Greer * Turbo codes Feb 29 Dan Daly * Connections between reduced decompositions and permutation patterns Feb 22 Brett Werner * Kakutani equivalence in minimal Cantor systems Feb 8 Aditya Nagrath * Properties of scattered lattices and the introduction of a meet semilattice duality (thesis defense) Feb 1 Andrew Dykstra (Colorado State) The weak equivalence relation in symbolic dynamics Jan 25 Astrid an Heuf (New South Wales) C-algebras associated to transformation groups Jan 18 Alvaro Arias Introduction to mathematical finance Jan 11 Deb Carney Flatland the movie Nov 9 Jenya Kirshtein * On the uniqueness of the weight enumerator of a perfect code Nov 2 Nic Ormes Tillings: Symmetric and Asymmetric Oct 26 Michael Kinyon Applications of automated reasoning to problems in quasigroup theory and loop theory Oct 19 Brett Werner * Entropy of Shifts of Finite Type (SFT) Oct 12 Poonam Singh * Fixed point theorems in uniform spaces II Oct 5 Poonam Singh * Fixed point theorems in uniform spaces I Sep 28 Nathan McNew * Inductive limits of ordered groups and continued fractions Sep 21 Sarah Campbell Inductive limits of groups

### 2006-2007

 Jun 1 Dan Daly * Permutation pattern avoidance May 25 Sarah Law 3Sum Hard Problems May 11 Brett Werner Substitution Systems (and their Entropy) to Bratteli Diagrams May 4 Jeff Farmer (Northern Colorado) What does a mathematician bring to teacher education? Apr 13 Jenya Kirshtein * Finite-difference solutions of the problem of biphase filtration in the porous medium Apr 6 Aditya Nagrath * The Jordan-Holder chain condition for semimodular lattices Mar 9 Shawn O?Donoghue * The Weierstrass approximation theorem Mar 2 Brett Werner * Bratteli diagrams and ordered groups Feb 23 Sarah Law * The ellipsoid method Feb 16 Petr Vojtechovsky Combinatorial problems as dynamical systems Jan 19 Kyle Pula * Gallai multigraphs Jan 12 Teiko Heinonen (Turku, Finland) Approximately repeatable measurements Nov 17 Petr Vojtechovsky Codes of variable length with a view toward Shannon's Noiseless Theorem Nov 10 Shlomo Reisner (Haifa) From regular polygons to algorithms for polytope approximation Nov 4 Michael Kinyon How to add vectors Oct 27 Brett Werner * Ordered groups of Bratteli diagrams Oct 20 Nic Ormes An introduction to chaos theory Oct 13 Aditya Nagrath * Scattered lattices II Oct 6 Aditya Nagrath * Scattered lattices Sep 29 Fernando Tohme (Departamento de Economia - Universidad Nacional del Sur, CONICET, Argentina) Formal limitations in economic theory and the alternative set theory AFA - + AD + AC Sep 22 Jonathan Poritz (Colorado State, Pueblo) Pure math in the news: Perelman and Poincare

### 2005-2006

 May 26 Joel Cohen Prime numbers and powers of 2: A computational perspective May 19 Aditya Nagrath * Representation of distributive lattices II May 12 Kurt Koltko A gauge theory of CPT transformations May 5 Cy Holladay * Queen domination Apr 28 Oscar Hasbun * Fast matrix multiplication II Apr 21 Jim Hagler Grothendieck inequality Apr 17 Merab Gogberashvili (Andronikashvili Institute of Physics, Tbilisi, Georgia) Octonionic geometry Apr 14 Stan Gudder Why quantum computers can do things ordinary computers cannot Mar 31 Alvaro Arias Stone-Weierstrass theorem Mar 10 Aditya Nagrath * Birkhoff's Theorem - Representation of distributive lattices Mar 3 Oscar Hasbun Fast matrix multiplication Feb 24 Rick Ball D5-T5 theorem Feb 17 Mark Tomforde (William and Mary) C*-algebras of directed graphs Feb 10 Adriana Nenciu (Florida) Number of character tables of finite groups Feb 3 Michael Kinyon (Indiana U South Bend) The Coquecigrue of a Leibniz Algebra: Recent Progress Jan 27 Rick Ball A little lattice theory Jan 20 Petr Vojtechovsky Sphere packings and lattices Jan 6 Kyle Pula * Mutually orthogonal Latin squares Nov 18 Trent Hampton On Riemann Hypothesis Nov 11 Wojciech Kosek (Colorado College) Dynamical methods in combinatorial number theory: history and some new results about prime numbers Nov 4 Sarah Law * An introduction to queuing theory Oct 28 Tricia Winning * Euclid's parallel postulate and the discovery of hyperbolic geometry Oct 14 Alvaro Arias Marriage theorem and decomposition of measures Oct 7 Claudio Delrieux (Universidad Nacional del Sur, Argentina) Fractal objects at the intersection of mathematics and computer science Sep 30 Nic Ormes Fractals : In between dimensions Sep 23 Rick Ball Selling pizza II Sep 16 Rick Ball Selling pizza

### 2004-2005

 May 20 Jonathan Von Stroh RSA cryptography and theoretical quantum implications May 13 Giorgio Ottaviani (U Florence, Italy) What is computational algebraic geometry? May 6 Cy Holladay * Knight's tours Apr 29 Bill Cherowitzo (UC Denver) On generalizing the concept of a conic Apr 22 Aditya Nagrath On downward order continuous and Priestley spaces Apr 15 Aditya Nagrath A dreaded counterexample Apr 8 Alvaro Arias Matrix inequalities Apr 1 Stan Payne (UC Denver) Quadratic equations over finite fields Feb 25 Sarah Law * Moebius maps Feb 18 Jim Hagler The dollar auction Feb 11 Frank Schroeck Entropy Feb 4 Kyle Pula * Polya theory of counting II Jan 21 Kyle Pula * Polya theory of counting I Jan 14 Dan Daly * Designs and projective planes Jan 7 Cy Holladay * Logic and formality Nov 17 Kyle Pula * Introduction to combinatorial design theory Nov 12 Chris Rasmussen (San Diego State University) A brief introduction to mathematics education research and an illustrative example Nov 5 Aditya Nagrath * Priestley spaces II Oct 29 Aitya Nagrath * Priestley spaces Oct 22 Sarah Law * The art gallery theorem Oct 15 Nic Ormes Entropy and symbolic dynamics Oct 8 Stan Gudder Entropy Oct 1 Petr Vojtìchovský Matrix games Sep 24 Alvaro Arias Introduction to cryptography

### 2003-2004

 May 28 Rick Ball On Stone-Weierstrass theorem May 21 Petr Vojtìchovský Projective plane of order 2 and its many disguises May 14 Aditya Nagrath * Priestley spaces with a few accumulation points II May 7 Aditya Nagrath * Priestley spaces with a few accumulation points I Apr 30 Alvaro Arias Antisymmetric tensor products and singular values Apr 23 Alvaro Arias Majorization of vectors in R n and eigenvalue estimates Apr 16 Nic Ormes Symbolic dynamics and the spectra of nonnegative matrices Apr 9 Stan Gudder On Kadison's theorem Mar 5 Brett Werner * Introduction to discrete dynamical systems Feb 27 Jennifer Proal * Knots Feb 20 Kimberly Wey * Banach-Tarski paradox Feb 13 Charles Holland (Bowling Green) Divisible ordered groups: A counterexample Feb 6 Nic Ormes Continuous fractions Jan 30 Jim Hagler Approximating real numbers by rational numbers Jan 16 Petr Vojtìchovský Magic squares Nov 14 Rick Ball On well-ordered sets II Nov 7 Mario Lopez The power of duality Oct 31 Rick Ball On well-ordered sets Oct 24 Nic Ormes Period 3 implies chaos