Proposals
Below are some proposals for talks from the past (and current). By clicking on the ID number, more details are shown. By default, these are sorted chronologically (recent first) and by then by last name. The data can be sorted by alternate means by using the links at the top right, each allowing ascending or descending orders.
Displaying 161-180 of 471 results.
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ID:
274
Year: 2010
Name: A. M. Fink
Institution: Iowa State University
Subject area(s):
Title of Talk: A New Look at IQ
Abstract: We will discuss the Isoperimetric Quotient for low order polygons. If time permits, we can illustrate its connection with some linear algebra and markov chains. There are some intriguing geometric open problems.
Year: 2010
Name: A. M. Fink
Institution: Iowa State University
Subject area(s):
Title of Talk: A New Look at IQ
Abstract: We will discuss the Isoperimetric Quotient for low order polygons. If time permits, we can illustrate its connection with some linear algebra and markov chains. There are some intriguing geometric open problems.
ID:
275
Year: 2010
Name: Irvin Hentzel
Institution: Iowa State University
Subject area(s): Teaching Calculus
Title of Talk: Ideas and Examples for Calculus
Abstract: We give some non traditional problems from various sources that help with the understanding of the ideas of calculus. We show how the concept of continuity can be used to get a better grasp of a situation and to correct bad judgement. The goal is not to show nice calculations, but to show ways of thinking.
Year: 2010
Name: Irvin Hentzel
Institution: Iowa State University
Subject area(s): Teaching Calculus
Title of Talk: Ideas and Examples for Calculus
Abstract: We give some non traditional problems from various sources that help with the understanding of the ideas of calculus. We show how the concept of continuity can be used to get a better grasp of a situation and to correct bad judgement. The goal is not to show nice calculations, but to show ways of thinking.
ID:
276
Year: 2010
Name: Jihyeok Choi
Institution: Iowa State University
Subject area(s): Graph theory
Title of Talk: Monotonicity of mixed Ramsey numbers
Abstract: For two graphs, G, and H, an edge-coloring of a complete graph is (G;H)-good if there is no monochromatic subgraph isomorphic to G and no rainbow subgraph isomorphic to H in this coloring. The set of number of colors used by some (G;H)-colorings of Kn is called a mixed-Ramsey spectrum. In this talk, we will discuss whether the spectrum is an interval. This is joint work with Maria Axenovich.
Year: 2010
Name: Jihyeok Choi
Institution: Iowa State University
Subject area(s): Graph theory
Title of Talk: Monotonicity of mixed Ramsey numbers
Abstract: For two graphs, G, and H, an edge-coloring of a complete graph is (G;H)-good if there is no monochromatic subgraph isomorphic to G and no rainbow subgraph isomorphic to H in this coloring. The set of number of colors used by some (G;H)-colorings of Kn is called a mixed-Ramsey spectrum. In this talk, we will discuss whether the spectrum is an interval. This is joint work with Maria Axenovich.
ID:
279
Year: 2010
Name: Christian Roettger
Institution: Iowa State University
Subject area(s): ODE, recurrence, power series, experimental mathematics
Title of Talk: Recurrences, power series, and ODE
Abstract: A three-term recurrence is connected to a power series, which solves a second-order ODE. The recurrence can be helpful in solving the ODE explicitly, and in approximating the power series. As is well-known, its growth rate is related to the radius of convergence of the power series. We will use a simple example straight from the textbook to investigate this in the case of a recurrence with *non-constant* coefficients. While the growth rate turns out to be surprisingly resistant to attack, it has great potential to be explored experimentally as well as theoretically - an opportunity for open-ended student projects.
Year: 2010
Name: Christian Roettger
Institution: Iowa State University
Subject area(s): ODE, recurrence, power series, experimental mathematics
Title of Talk: Recurrences, power series, and ODE
Abstract: A three-term recurrence is connected to a power series, which solves a second-order ODE. The recurrence can be helpful in solving the ODE explicitly, and in approximating the power series. As is well-known, its growth rate is related to the radius of convergence of the power series. We will use a simple example straight from the textbook to investigate this in the case of a recurrence with *non-constant* coefficients. While the growth rate turns out to be surprisingly resistant to attack, it has great potential to be explored experimentally as well as theoretically - an opportunity for open-ended student projects.
ID:
26
Year: 2004
Name: Ryan Martin
Institution: Iowa State University
Subject area(s): Combinatorics, Graph Theory
Title of Talk: Six degrees of graph theory: Kevin Bacon, Paul Erdos, William McKinley and me
Abstract: Popularized by the Kevin Bacon game, the Small World problem is a question of measuring distance between members of a given set, upon which is a binary symmetric relationship. In the game, the set is the set of actors and two actors are linked if they appeared in the same movie. The distance between two actors is the fewest number of links to get from one to the other. In this talk, we discuss the game and a random graph model that gives an answer to a Small World-type question.
Year: 2004
Name: Ryan Martin
Institution: Iowa State University
Subject area(s): Combinatorics, Graph Theory
Title of Talk: Six degrees of graph theory: Kevin Bacon, Paul Erdos, William McKinley and me
Abstract: Popularized by the Kevin Bacon game, the Small World problem is a question of measuring distance between members of a given set, upon which is a binary symmetric relationship. In the game, the set is the set of actors and two actors are linked if they appeared in the same movie. The distance between two actors is the fewest number of links to get from one to the other. In this talk, we discuss the game and a random graph model that gives an answer to a Small World-type question.
ID:
282
Year: 2010
Name: Brian Patterson
Institution: Iowa State University
Subject area(s): Real Analysis, Computability Theory
Title of Talk: Multi-Resolution Cellular Automata for Real Computation
Abstract: We will first briefly review cellular automata and why representing and computing with real numbers with a computer is problematic. Then we will discuss a new approach that uses the concept of fissioning cells to approximate real-valued regions. I will close with a brief explanation of my simulator.
Year: 2010
Name: Brian Patterson
Institution: Iowa State University
Subject area(s): Real Analysis, Computability Theory
Title of Talk: Multi-Resolution Cellular Automata for Real Computation
Abstract: We will first briefly review cellular automata and why representing and computing with real numbers with a computer is problematic. Then we will discuss a new approach that uses the concept of fissioning cells to approximate real-valued regions. I will close with a brief explanation of my simulator.
ID:
285
Year: 2010
Name: Reza Rastegar
Institution: Iowa State University
Subject area(s): Probability
Title of Talk: Random walks in a sparse ``cookie" environment
Abstract: ``Cookie random walks" is a popular model of self-interacting random walks. Several variations of this model have been studied during the last decade. In this talk we will focus on the random walk on the integer lattice, where the ``cookies" perturbing the random walk are placed in a regular random sub-lattice of Z. We will present the model, briefly discuss an associated branching process, and then state criteria for transience and recurrence for this random walk.
Year: 2010
Name: Reza Rastegar
Institution: Iowa State University
Subject area(s): Probability
Title of Talk: Random walks in a sparse ``cookie" environment
Abstract: ``Cookie random walks" is a popular model of self-interacting random walks. Several variations of this model have been studied during the last decade. In this talk we will focus on the random walk on the integer lattice, where the ``cookies" perturbing the random walk are placed in a regular random sub-lattice of Z. We will present the model, briefly discuss an associated branching process, and then state criteria for transience and recurrence for this random walk.
ID:
288
Year: 2010
Name: Travis Peters
Institution: Iowa State University
Subject area(s):
Title of Talk: Minimum rank, maximum nullity and zero forcing number for selected graph families
Abstract: The minimum rank of a simple graph G is defined to be the smallest possible rank over all symmetric real matrices whose ijth entry is nonzero whenever {i, j} is an edge in G and is zero otherwise. Maximum nullity is taken over the same set of matrices. The zero forcing number is the minimum size of a zero forcing set of vertices and bounds the maximum nullity from above. This talk discusses the graph families ciclos and estrellas. In particular, these families provide the examples showing that the maximum nullity of a graph and its dual may differ, and similarly for zero forcing number.
Year: 2010
Name: Travis Peters
Institution: Iowa State University
Subject area(s):
Title of Talk: Minimum rank, maximum nullity and zero forcing number for selected graph families
Abstract: The minimum rank of a simple graph G is defined to be the smallest possible rank over all symmetric real matrices whose ijth entry is nonzero whenever {i, j} is an edge in G and is zero otherwise. Maximum nullity is taken over the same set of matrices. The zero forcing number is the minimum size of a zero forcing set of vertices and bounds the maximum nullity from above. This talk discusses the graph families ciclos and estrellas. In particular, these families provide the examples showing that the maximum nullity of a graph and its dual may differ, and similarly for zero forcing number.
ID:
548
Year: 2019
Name: Christian Roettger
Institution: Iowa State University
Subject area(s):
Title of Talk: Balanced Numbers and Balanced Primes
Abstract: Balanced numbers are odd natural numbers n which have an equal number of 0s and 1s in the periodic part of the base-2 representation of their reciprocal 1/n. We present some insights about balanced numbers that use just elementary Number Theory like the Quadratic Reciprocity Theorem. In particular, if a prime p is congruent to 3 or 5 modulo 8, then p is balanced. If a prime p is congruent to 7 modulo 8, then p is not balanced. All powers of p are balanced iff p is. The case of primes congruent to 1 modulo 8 is much more difficult. Hasse made a breakthrough in 1966, showing that the balanced primes have a Dirichlet density of 17/24. We have refined Hasse's result slightly. Another question is how big is the set of balanced numbers (not only primes) less than x? Using a method due to Landau, we can show that this is bounded above by C x/log^(1/4) (x) and below by D x / log^(3/4)(x), with constants C, D > 0. I solemnly promise that I won't go into the gory detail, only highlight the beautiful and accessible parts of the subject. The second part of the talk is joint work with Joshua Zelinsky.
Year: 2019
Name: Christian Roettger
Institution: Iowa State University
Subject area(s):
Title of Talk: Balanced Numbers and Balanced Primes
Abstract: Balanced numbers are odd natural numbers n which have an equal number of 0s and 1s in the periodic part of the base-2 representation of their reciprocal 1/n. We present some insights about balanced numbers that use just elementary Number Theory like the Quadratic Reciprocity Theorem. In particular, if a prime p is congruent to 3 or 5 modulo 8, then p is balanced. If a prime p is congruent to 7 modulo 8, then p is not balanced. All powers of p are balanced iff p is. The case of primes congruent to 1 modulo 8 is much more difficult. Hasse made a breakthrough in 1966, showing that the balanced primes have a Dirichlet density of 17/24. We have refined Hasse's result slightly. Another question is how big is the set of balanced numbers (not only primes) less than x? Using a method due to Landau, we can show that this is bounded above by C x/log^(1/4) (x) and below by D x / log^(3/4)(x), with constants C, D > 0. I solemnly promise that I won't go into the gory detail, only highlight the beautiful and accessible parts of the subject. The second part of the talk is joint work with Joshua Zelinsky.
ID:
293
Year: 2010
Name: Kenneth Driessel
Institution: Iowa State University
Subject area(s):
Title of Talk: Continuous Problems Are Easier Than Discrete Ones
Abstract: I claim: Continuous problems are (usually) easier than analogous discrete problems. Consequently, when teaching, we should emphasize the relation between continuous and discrete problems whenever possible. I shall use a historical example to support my claim. In particular, I shall review J.W.S. Rayleigh's treatment of beaded and continuous strings, which appears in his book "Theory of Sound" (Macmillan, 1894).
Year: 2010
Name: Kenneth Driessel
Institution: Iowa State University
Subject area(s):
Title of Talk: Continuous Problems Are Easier Than Discrete Ones
Abstract: I claim: Continuous problems are (usually) easier than analogous discrete problems. Consequently, when teaching, we should emphasize the relation between continuous and discrete problems whenever possible. I shall use a historical example to support my claim. In particular, I shall review J.W.S. Rayleigh's treatment of beaded and continuous strings, which appears in his book "Theory of Sound" (Macmillan, 1894).
ID:
295
Year: 2010
Name: Ranojoy Basu
Institution: Iowa State University
Subject area(s): Mathematical Finance
Title of Talk: Expected Utility Maximization in an Optimal stopping Environment
Abstract: In this paper we study an investment problem where an investor has the option to invest in a risk free asset (such as a bank account ) and a risky asset. His wealth can be transferred between the two assets and there are no transaction costs. The proportion of wealth in the risky asset is a priori chosen deterministic function of wealth. The objective is to …nd an optimal quitting time which maximizes the expected discounted utility from terminal wealth. First, we consider a situation when the wealth process is not subject to bankruptcy and obtain an optimal quitting time. Second, we consider the more realistic scenario when an investor’s wealth is subject to default. We develop necessary mathematical techniques to obtain an optimal selling time in both the circumstances. In both cases, it turned out that the optimal selling time is of threshold type. Numerical methods can easily be implemented to compute the optimal threshold.
Year: 2010
Name: Ranojoy Basu
Institution: Iowa State University
Subject area(s): Mathematical Finance
Title of Talk: Expected Utility Maximization in an Optimal stopping Environment
Abstract: In this paper we study an investment problem where an investor has the option to invest in a risk free asset (such as a bank account ) and a risky asset. His wealth can be transferred between the two assets and there are no transaction costs. The proportion of wealth in the risky asset is a priori chosen deterministic function of wealth. The objective is to …nd an optimal quitting time which maximizes the expected discounted utility from terminal wealth. First, we consider a situation when the wealth process is not subject to bankruptcy and obtain an optimal quitting time. Second, we consider the more realistic scenario when an investor’s wealth is subject to default. We develop necessary mathematical techniques to obtain an optimal selling time in both the circumstances. In both cases, it turned out that the optimal selling time is of threshold type. Numerical methods can easily be implemented to compute the optimal threshold.
ID:
296
Year: 2010
Name: Subhra Bhattacharya
Institution: Iowa State University
Subject area(s): Mathematical Finance
Title of Talk: Stock Loan Subject to Bankruptcy
Abstract: In this paper, risk of bankruptcy has been introduced in the valuation of a financial derivative called stock loan. Bankruptcy has been modelled in both structural and reduced form approach. In structural form model, stock loan with finite maturity is considered following the Black-Cox specification of bankruptcy. It has been shown that the valuation of such an asset can be obtained explicitly in terms of the distribution of the first hitting time of Brownian motion and the pricing of the barrier options. In reduced form model, the default intensity has been introduced as in hazard rate models. A closed form solution of the initial value function is obtained, which implicitly defines the optimal exercise boundary. Moreover, this value function reflects an interrelationship between the optimal loan amount and the relevant variables (e.g. loan interest rate, stock price volatility etc). This interrelationship can be used to explain interesting issues such as: how does stock price volatility (or the reputation of the stock) or the loan interest rate affects the optimal loan amount?
Year: 2010
Name: Subhra Bhattacharya
Institution: Iowa State University
Subject area(s): Mathematical Finance
Title of Talk: Stock Loan Subject to Bankruptcy
Abstract: In this paper, risk of bankruptcy has been introduced in the valuation of a financial derivative called stock loan. Bankruptcy has been modelled in both structural and reduced form approach. In structural form model, stock loan with finite maturity is considered following the Black-Cox specification of bankruptcy. It has been shown that the valuation of such an asset can be obtained explicitly in terms of the distribution of the first hitting time of Brownian motion and the pricing of the barrier options. In reduced form model, the default intensity has been introduced as in hazard rate models. A closed form solution of the initial value function is obtained, which implicitly defines the optimal exercise boundary. Moreover, this value function reflects an interrelationship between the optimal loan amount and the relevant variables (e.g. loan interest rate, stock price volatility etc). This interrelationship can be used to explain interesting issues such as: how does stock price volatility (or the reputation of the stock) or the loan interest rate affects the optimal loan amount?
ID:
305
Year: 2011
Name: Travis Peters
Institution: Iowa State University
Subject area(s):
Title of Talk: Zero forcing number, maximum nullity, and path cover number of complete edge subdivision graphs
Abstract: The minimum rank of a simple graph G is defined to be the smallest possible rank over all symmetric real matrices whose ijth entry is nonzero whenever {i, j} is an edge in G and is zero otherwise. Maximum nullity is taken over the same set of matrices. The zero forcing number is the minimum size of a zero forcing set of vertices and bounds the maximum nullity from above. The path cover number is the fewest number of vertex disjoint induced paths that cover all the vertices of the graph. We study the effect of edge subdivisions of a graph on the zero forcing number, maximum nullity, and path cover number.
Year: 2011
Name: Travis Peters
Institution: Iowa State University
Subject area(s):
Title of Talk: Zero forcing number, maximum nullity, and path cover number of complete edge subdivision graphs
Abstract: The minimum rank of a simple graph G is defined to be the smallest possible rank over all symmetric real matrices whose ijth entry is nonzero whenever {i, j} is an edge in G and is zero otherwise. Maximum nullity is taken over the same set of matrices. The zero forcing number is the minimum size of a zero forcing set of vertices and bounds the maximum nullity from above. The path cover number is the fewest number of vertex disjoint induced paths that cover all the vertices of the graph. We study the effect of edge subdivisions of a graph on the zero forcing number, maximum nullity, and path cover number.
ID:
309
Year: 2011
Name: Irvin Hentzel
Institution: Iowa State University
Subject area(s): First Semester Calculus, Group Work
Title of Talk: Group Activities In Calculus
Abstract: I have been devoting one day a week to group work in calculus. I show the type of activities that I have used. I have some data on the interest shown, and how these group scores compare with the traditional tests scores.
Year: 2011
Name: Irvin Hentzel
Institution: Iowa State University
Subject area(s): First Semester Calculus, Group Work
Title of Talk: Group Activities In Calculus
Abstract: I have been devoting one day a week to group work in calculus. I show the type of activities that I have used. I have some data on the interest shown, and how these group scores compare with the traditional tests scores.
ID:
319
Year: 2011
Name: Elgin Johnston
Institution: Iowa State University
Subject area(s): Math Education
Title of Talk: The ALEKS Placement Assessment at Iowa State University
Abstract: We are in the process of introducing a new Mathematics placement tool at Iowa State University. This presentation will give some information about the ALEKS system, our background with it, and discuss some preliminary results from our analysis of the effectiveness of the tool.
Year: 2011
Name: Elgin Johnston
Institution: Iowa State University
Subject area(s): Math Education
Title of Talk: The ALEKS Placement Assessment at Iowa State University
Abstract: We are in the process of introducing a new Mathematics placement tool at Iowa State University. This presentation will give some information about the ALEKS system, our background with it, and discuss some preliminary results from our analysis of the effectiveness of the tool.
ID:
64
Year: 2004
Name: Christian Roettger
Institution: Iowa State University
Subject area(s): Number theory, exponential sums
Title of Talk: Uniform distribution and invertible matrices
Abstract: Uniform distribution is usually known as a property of sequences xn in the unit interval, like n alpha modulo 1, where alpha is irrational. We will present an example of uniform distribution in the unit square, explain the handy Weyl criterion used to prove uniform distribution, and conclude with an application to invertible 2x2 - matrices over the integers.
Year: 2004
Name: Christian Roettger
Institution: Iowa State University
Subject area(s): Number theory, exponential sums
Title of Talk: Uniform distribution and invertible matrices
Abstract: Uniform distribution is usually known as a property of sequences xn in the unit interval, like n alpha modulo 1, where alpha is irrational. We will present an example of uniform distribution in the unit square, explain the handy Weyl criterion used to prove uniform distribution, and conclude with an application to invertible 2x2 - matrices over the integers.
ID:
65
Year: 2004
Name: Tauqir Bibi
Institution: Iowa State University
Subject area(s): Calculus
Title of Talk: Experiences of Tauqir Bibi in Teaching Calculus Courses
Abstract: I have taught calculus courses for many years. Most of the students in these courses are engineering majors. Many of these students appreciate seeing applications to their majors. I will present examples of some problems and projects that introduce students to applications of Calculus in their majors.
Year: 2004
Name: Tauqir Bibi
Institution: Iowa State University
Subject area(s): Calculus
Title of Talk: Experiences of Tauqir Bibi in Teaching Calculus Courses
Abstract: I have taught calculus courses for many years. Most of the students in these courses are engineering majors. Many of these students appreciate seeing applications to their majors. I will present examples of some problems and projects that introduce students to applications of Calculus in their majors.
ID:
71
Year: 2004
Name: Irvin Hentzel
Institution: Iowa State University
Subject area(s):
Title of Talk: The mathematics of navigation in aviation
Abstract: We explain the how and why of Compass errors and how to work around them. We discuss the NDB (non-directional beacon) and the geometry behind its use for navigation. We mention the Precision approach. And we present some contradictions from explaining lift by using Bernoulli's theorem.
Year: 2004
Name: Irvin Hentzel
Institution: Iowa State University
Subject area(s):
Title of Talk: The mathematics of navigation in aviation
Abstract: We explain the how and why of Compass errors and how to work around them. We discuss the NDB (non-directional beacon) and the geometry behind its use for navigation. We mention the Precision approach. And we present some contradictions from explaining lift by using Bernoulli's theorem.
ID:
75
Year: 2004
Name: Stephen Willson
Institution: Iowa State University
Subject area(s): graph theory
Title of Talk: Building supertrees using distances
Abstract: Suppose that a family of rooted phylogenetic trees Ti with different sets Xi of leaves is given. A supertree for the family would be a single rooted tree T whose leaf set is the union of all the Xi, such that the branching information in T corresponds to the branching information in all the trees Ti. This talk proposes a polynomial-time method BUILD-WITH-DISTANCES that makes essential use of distance information provided on the trees Ti to construct a rooted tree T. When a supertree containing also the distance information exists, then the method produces a supertree T. This supertree often shows increased resolution over the trees found by methods that utilize only the topology of the input trees.
Year: 2004
Name: Stephen Willson
Institution: Iowa State University
Subject area(s): graph theory
Title of Talk: Building supertrees using distances
Abstract: Suppose that a family of rooted phylogenetic trees Ti with different sets Xi of leaves is given. A supertree for the family would be a single rooted tree T whose leaf set is the union of all the Xi, such that the branching information in T corresponds to the branching information in all the trees Ti. This talk proposes a polynomial-time method BUILD-WITH-DISTANCES that makes essential use of distance information provided on the trees Ti to construct a rooted tree T. When a supertree containing also the distance information exists, then the method produces a supertree T. This supertree often shows increased resolution over the trees found by methods that utilize only the topology of the input trees.
ID:
331
Year: 2012
Name: Christian Roettger
Institution: Iowa State University
Subject area(s): Multivariate Calculus, numerical mathematics
Title of Talk: Calculus III projects for Undergraduates
Abstract: Multivariate Calculus lends itself particularly well to explorations on the computer. Examples include Newton's method, Steepest Descent, two-dimensional Riemann sums, Euler's method for differential equations. Each of these can be presented in various appealing contexts and is immediately plausible for a student who understands the core concepts of the derivative of a multivariate function and Riemann sums, respectively. On the other hand, exploring the 'approximation' aspect of Calculus with paper and pencil and even with a calculator is less satisfactory than using a computer, especially if powerful mathematical software is available (eg SAGE, R, Matlab, Maple, Mathematica). Ideally, the results can be presented in an appealing graphic, and we'll show examples of student work. Finally, we do not assume any programming skills, but this kind of small project is a great opportunity to learn them.
Year: 2012
Name: Christian Roettger
Institution: Iowa State University
Subject area(s): Multivariate Calculus, numerical mathematics
Title of Talk: Calculus III projects for Undergraduates
Abstract: Multivariate Calculus lends itself particularly well to explorations on the computer. Examples include Newton's method, Steepest Descent, two-dimensional Riemann sums, Euler's method for differential equations. Each of these can be presented in various appealing contexts and is immediately plausible for a student who understands the core concepts of the derivative of a multivariate function and Riemann sums, respectively. On the other hand, exploring the 'approximation' aspect of Calculus with paper and pencil and even with a calculator is less satisfactory than using a computer, especially if powerful mathematical software is available (eg SAGE, R, Matlab, Maple, Mathematica). Ideally, the results can be presented in an appealing graphic, and we'll show examples of student work. Finally, we do not assume any programming skills, but this kind of small project is a great opportunity to learn them.