Division of Science





Department of Mathematics
The City College of New York
160 Convent Avenue
New York, NY 10031

Phone: (212) 650-5346
Fax: (212) 650-6294

Math Club

All talks

  • Thursday, April 14, 2011, 01:00PM, NAC 6-113

    Ethan Akin (CCNY), Dynamic Fractals a la Furstenberg

    There are two ideas associated with fractals. According to one a fractal is a set with fractional dimension. The one I will be considering is that a fractal is a set which exhibits self-similarity. As you blow up the scale near a point the scaled-up figures repeatedly look like the original. Furstenberg introduced a natural dynamic notion of what it means for a closed subset of a square to be a fractal at one of its points. This is the concept I will describe, replacing the square by the sequence space on a finite number of symbols.

    Remark: This will follow the Undergraduate Awards Ceremony held in NAC 8/133B at noon.

  • Tuesday, May 12, 2009, 12:30PM, NAC 4113

    Ranja Reda (Vienna University of Technology), Rotational Invariant Importance Sampling

    A new importance sampling technique to increase the efficiency of rare event simulation. By using a multidimensional rotational invariant auxiliary density, this method can be applied to estimate risk measures for credit risk portfolios where the method of importance sampling via mean shifting is not applicable. This is especially the case in inhomogeneous portfolios, i.e. portfolios with multiple areas of high losses. Furthermore, rotational invariant importance sampling allows calculating contributions to risk measures of different customer clusters in credit porfolios quicker and more precisely.

    Our new model, rotational invariant importance sampling has already been implemented in Bank Austria's system. Their main credit portfolio with about 2000 clients is already measured through our new simulation technique. As you can imagine there was lot of work to be done as far as the calibration of the model, finding the optimal parameters for the new importance sampling density, etc.

  • Thursday, April 30, 2009, 12:30PM, NAC 6/114

    Rochelle (Shelley) Ring (CCNY), Becoming a High School Mathematics Professor

    Come join us on April 30 in NAC 6/114 12:30-1:30 to learn about an exciting career opportunity! If you are looking for a rewarding, satisfying and secure profession, come learn about how you can become a high school mathematics teacher and begin working at a wonderful job right after college. Light refreshments will be provided at the meeting.

  • Tuesday, April 28, 2009, 12:30PM, NAC 4113

    Rene Ardila (CCNY), Matrix Number Theory: Factorization in Integral Matrix Semigroups

    Factorization theory is a prominent field of mathematics; however, most previous research in this area lies in the commutative case. Noncommutative factorization theory is a relatively new topic of interest. This talk examines the factorization properties of noncommutative atomic semigroups of matrices, including results on the minimum and maximum length of atomic factorizations, the elasticity and the delta set of the semigroups.

    This talk is suitable for those who have had linear algebra.

  • Tuesday, March 10, 2009, 12:30PM, NAC 4113

    Michael Levin (Department of Philosophy), Category Theory as a Structuralist Foundation for Mathematics

    It is often said that mathematics studies "structure," an idea that has been picked up by a number of philosophers. This idea has certain advantages over thinking of mathematics as a body of inferences from uninterpreted postulates, and also the platonistic idea that, e.g., number theory is about Numbers. Category theory might be thought of as "structuralism in action." I will illustrate this idea with a discussion of the "number objects" in arbitrary categories. Time permitting, I will say a little about the category axioms themselves.

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