# Current Academic Year Seminars

### BLOCK 4, 2015 - November/December

**Friday, November 20th at 2:30pm**

**TSC 229**

**Michael Penn**

Speaker:

Speaker:

**"The Universality of the Virasoro Algebra in Mathematics and Physics"**

Title:

Title:

**Rated: **PG-13

**Abstract: **The study of representation theory is, in essence, the reduction of the study of abstract algebraic structures to linear algebra — the study of vector spaces and linear transformations. The Virasoro algebra finds its way into the representation theory of all suitably interesting Lie algebras. During this talk, we will explore the Virasoro algebra by its definition, its appearance in the representations of other Lie algebras, and its applications to the seeming disparate subjects of number theory and physics.

This talk will provide all of the necessary definitions and consider several in depth examples, a strong knowledge of linear algebra is all that is required for full understanding.

*

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### BLOCK 3, 2015 - October/November

**Friday, November 6th, at 2:30pm****TSC 229****Speaker**: Steven Janke**Title**: "The Central Limit Theorem: More of the Story"

**Abstract**: Undergraduate probability courses present a version of the Central Limit Theorem published in 1810. Basically, it claims (under certain constraints) that the sum of several random variables converges to the normal distribution (bell-shaped curve). For statistics, one result of the theorem is that the sample mean is approximately normal. Yet, the common version of the theorem is really only the beginning of a series of results that start to explain why, for example, experimental errors are nearly normally distributed. This talk will trace these results, along with the development of the relevant analysis, and highlight the more recent connections with entropy and the second law of thermodynamics.

**Rated**: PG13 with R sections (A lot of undergraduate with some graduate mathematics or computer science assumed.)

*

**Friday, October 30th, at 2:30pm****TSC 122 Kresge Lecture Hall****Speaker**: Jeff Treviño, Assistant Professor of Music and Technology at CC**Title**: "One Through Eight...Except Five: Problems and Potentials of Computationally Represented and Processed Music Notation"

**Abstract**: For over four decades, music researchers have attempted to computationally model common practice Western music notation and a canonic repertoire of symbolic manipulations thereof. I'll introduce some of the basic representational and processing challenges of this field (with an emphasis on rhythmic notation), review some of my research team's novel solutions, and finally demonstrate some of the artistic applications of Python programming in our team's creative work as composers.

**Rated**: PG

*

**Friday, October 23rd, at NOON****TSC 122 Kresge Lecture Hall****Pizza Provided **

**Speaker**: Amy Hepner '09

**Title**: "The Analytics of Social Progress."

**Abstract**: Come explore how the ideas of data science are being used to inform social progress efforts. Examples include: Predicting police officers at an increased risk of having an adverse interaction with the public; identifying students in danger of not graduating on time; improving environmental advocacy programs; identifying causes of home abandonment.

Mathematical concepts will be explained in everyday language. Career opportunities presented throughout.

**Rated**: G

*

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### BLOCK 2, 2015 - September/October

*****

**Friday, October 9th at NOON**

TSC 122 Kresge Lecture Hall**Pizza Provided Speaker:** Sarah Fletcher Mercaldo, Vanderbilt University

**Title:**"Best Practices for Constructing and Applying Clinical Prediction Models in the Presence of Non-Ignorable Missing Data"

**Rated: **PG-13

**Abstract: **Clinical prediction models use clinical and demographic information to predict the probability that a patient has a certain disease or clinical status. When patient data is missing, care must be taken in both constructing and applying the prediction model. In this presentation, I will introduce different types of missing data often observed in clinical and electronic medical record data. While certain kinds of missing data can be imputed successfully with simple or fancy imputation schemes, the most complicated case when the data are missing NOT at random presents substantial problems for researchers. Here I present several strategies for imputing data that are missing NOT at random and I evaluate and compare the performance of these strategies.

For demonstration, I will use the TREAT risk prediction model, which was developed from a cohort of 492 participants with known or suspected lung cancer evaluated for lung surgery. In this cohort 264 patients had complete data, and 228 patients were missing at least one predictor. When a physician is applying the TREAT model at the bedside to a patient, he may not know or have access to all the information the model requires, and thus how that data is imputed becomes critical to the application of the model. Prediction models such as the TREAT model are being used more frequently to inform clinical decisions. However, published prediction models cannot be applied when a patients clinical data is missing. Proper handling of missing data is key to developing a robust and accurate prediction model

*

**Friday, October 2nd at NOONTSC 122 - Kresge Lecture HallPizza will be provided!**

**Speaker:** Benjamin Ylvisaker**Title:** "Google, The NSA and The Supreme Leader are Listening!"

**Rated:** PG

**Abstract:** There is an enormous amount of private data sent and stored insecurely over the Internet. Powerful governmental, corporate and/or criminal organizations are actively collecting and exploiting this data. This talk will introduce a broad range of concepts in

information security and privacy. In particular we will discuss new ideas related to storing data securely in public cloud storage services.

All majors must write up four talks in order to graduate. Talk write ups should be submitted through Canvas. If you wish to be added to the Canvas page, please contact one of the paraprofs.

*

**Friday, September 4th at 2:30pm in TSC 229****Speaker:** Darren Funk-Neubauer**Title:** "Bidiagonal Pairs and Bidiagonal Triples." **Rated:** PG-13 with R rated sections**Abstract:** Roughly speaking, a bidiagonal pair is a pair of diagonalizable linear transformations on a finite-dimensional vector space, each of which acts in a bidiagonal fashion on the eigenspaces of the other. A classification of bidiagonal pairs will be presented. Then I will describe how to construct all bidiagonal pairs using representations of the Lie algebra sl_{2} and the quantum group *U*_{q} (sl_{2}) . Next, I will explain how to extend the definition of bidiagonal pair to a triple of linear transformations, thus defining a bidiagonal triple. I will discuss in what sense a given bidiagonal pair determines a bidiagonal triple. Lastly, I will describe the classification of bidiagonal triples.

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**BLOCK 1, 2015 - August/September**

Departmental Research Overview and Ice Cream Social

Friday, September 4th at NOON

TSC 122 - Tutt Science Lecture Hall

**Rated** G

This general-audience talk will showcase the various research interests of the Department of Mathematics and Computer Science at Colorado College. Each faculty member will provide a brief description of their scholarly pursuits. *Pizza will be provided!*

Faculty speakers will include

• Marlow Anderson - Wild Automorphisms of the Complex Plane, History of Mathematics

• David Brown - Mathematical Biology

• Andrea Bruder - Differential Equations

• Rodney James - Tropical Geometry

• Steven Janke – Computational Complexity

• Molly Moran - Geometric Group Theory

• Stefan Erickson - Computational Number Theory and Cryptography.

Immediately after the talk, we will be hosting an ice cream social for all students in the department lounge on the second floor of Tutt Science

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