## Spring 1999

[ 4/19/99 | 4/15/99 | 4/9/99 | 4/8/99 | 4/5/99 | 3/29/99 | 3/22/99 | 2/17/99 | 2/12/99 | 2/8/99 | 2/1/99 ]

**4/19/99 - Network Security Assessment
**Erik Birkholz

Ernst & Young

eSecurity Group

Erik Pace Birkholz is a Dickinson College Computer Science Graduate. While at Dickinson College he was an intern at the National Computer Security Association. Erik is now part of Ernst & Young's elite eSecurity group, a team of computer security professionals providing a sense of security to an insecure world of technology. This presentation will discuss methodologies, techniques, and tools used to assess the networks of Fortune 500 companies. Additionally, best practices for securing your networks will be discussed.

**4/15/99 -Software Engineering: The Model-View-Controller Design Pattern
**Special Thursday Chat: 12:20 pm in South College 250.

Mark Lattanzi

Department of Computer Science

James Madison University

I will be presenting a brief overview of what a design pattern is and showing several examples in Java of the MVC (or Observer) design pattern. Using this pattern allows for the separation of the application specific code from the UI code. It makes for a very clean, easily maintainable software product that can be developed in parallel by several programmers and easily integrated after all of the pieces have been created.

Goals:

To provide an understanding of the MVC design pattern through a series of examples.

To reinforce and encourage modular design and encapsulation in the development of software.

Prerequisite Knowledge:

Fundamentals from a CS1 course

Knowledge of an OO language (preferably Java)

A basic understanding of the software development process (life cycle)

**4/9/99 - Practical Applications of Coding Theory
**Special Friday Chat: 12:00 pm in South College 250.

Chris Boner

Department of Mathematics

University of Virginia

Coding theory addresses the problem of communicating over a noisy channel. Regardless of the medium, when messages are transmitted digitally it is impossible to guarantee that all digits will be received correctly. Coding means adding redundancy to messages so that codewords are further differentiated and errors may be detected and, hopefully, corrected. This talk will motivate the main issues of coding theory through a small example and illuminate many interesting applications of error-correcting codes. The simple yet widespread ISBN code will be examined in detail.

**4/8/99 - Should I make Cookies or Brownies?
**Special Thursday Chat: 12:20 pm in South College 250.

Megan Deeney

Department of Mathematics

Johns Hopkins University

This talk will present a simple, graphical approach to a two-variable linear program.

**4/5/99 - Dial "M" for Mathematics
**Dr. Barry Tesman

Department of Mathematics and Computer Science

Dickinson College

This talk will be about the relationship between mathematics and telephone numbers. Telephone numbers have been a source of amusement, (embarassment,) mathematical recreation and theoretical motivation. I will introduce you to a little bit of each.

**3/29/99 - Components - The Good, The Bad, and The Ugly
**David G. Stahl

Stoner Associates

This talk will discuss software components. The component philosophy will be explained, the use of components will be motivated, examples of components will be given and their advantages and disadvantages will be discussed.

**3/22/99 - High Fives (How to Solve Quintic Equations when necessary)
**Thomas Drucker

Last semester we saw that there are fifth degree polynomial equations that can't be solved by a formula involving radicals. There are, however, some fifth degree equations that need to be solved. The Japanese mathematician Kenkichi Iwasawa did some complicated work in number theory that turned out to furnish a way to write down solutions to quintic equations that can be solved. This talk will skip the complicated part and explain how, as in the case of Fermat's Last Theorem, abstract mathematics can have some very concrete applications.

**2/17/99 - From Kepler's Monsters to Thurston's Doughnut
**Special Wedensday 1:00pm Chat

Samuel Kaplan

Department of Mathematics

Bowdoin College

Tilings, the filling of a plane by regular shapes, are all around us. Brick buildings, bathroom floors, and insect eyes are all made up of tilings. We will explore how to fill a plane with regular polygons, odd shapes and aperiodic tilings. We will also look at the history and geometry of tilings, from Islamic mosaics, to Penrose tiles, from Kepler's monsters to Thurston's doughnut.

**2/12/99 - Meet the Composition Algebras
**Derek Smith

Department of Mathematics

Princeton University

You may have heard of R and C,

But H and O? What could they be?

I'll introduce you to all four

and tell you why there are no more.

**2/8/99 - The Mathematics of the Willow Flute
**Rachel Hall

Department of Mathematics

Penn State University

A flute looks like a tube with holes (at least that's how mathematicians see it). By covering or uncovering the holes, the player sounds different notes. The Norwegian willow flute has no holes, yet a skillful player can still produce many different tones. How is this? The answer lies in the mathematics governing the behavior of sound waves. We will learn how the willow flute works, and, incidentally, why the series 1 + 1/2 + 1/3 + 1/4 + 1/5 + 1/6 + 1/7 + 1/8 + ... is called the harmonic series---it really does have to do with music!

**2/1/99 - Sorting Algorithms
**Grant Braught

Department of Mathematics and Computer Science

Dickinson College

What is the fastest way to sort a list of numbers? We will look at several simple sorting methods. We will also prove that any algorithm based on comparisions between the numbers will require a minimum of n lg n comparisions. However, if we can find a way to sort the numbers without comparing them then it might be possible to sort the numbers more quickly. We will look at several algorithms which sort numbers without comparing them and at the conditions that limit their applicability.