Harvard University Math Department

Talk begins at 4:30, reception begins at 5:30, snacks provided.

**Speaker:**Joe Harris (Harvard)**Title:**Poncelet's theorem and the birth of modern algebraic geometry**Abstract:**In the early 19th century, Poncelet asked a simple question: given two ellipses in the plane, one inside the other, does there exist a polygon inscribed in the outer one and circumscribed about the inner? In this talk, I'll describe the (somewhat surprising) answer, and also describe how consideration of this simple problem led to two major changes in how we do algebraic geometry: the introduction of projective space, and the use of complex numbers.

**Speaker:**Martin Nowak (Harvard)**Title:**The Mathematics of Cooperation**Abstract:**Cooperation means that one individual pays a cost for another to receive a benefit. Cooperation can be at variance with natural selection: Why should you help a competitor? Yet cooperation is abundant in nature and is an important component of evolutionary innovation. Cooperation can be seen as the master architect of evolution and as the third fundamental principle of evolution beside mutation and selection. I will present mathematical principles of cooperation.

**Speaker:**Joe Harris (Harvard)**Title:**Poncelet's theorem and the birth of modern algebraic geometry**Abstract:**In the early 19th century, Poncelet asked a simple question: given two ellipses in the plane, one inside the other, does there exist a polygon inscribed in the outer one and circumscribed about the inner? In this talk, I'll describe the (somewhat surprising) answer, and also describe how consideration of this simple problem led to two major changes in how we do algebraic geometry: the introduction of projective space, and the use of complex numbers.

**Speaker:**Bill Dunham (Harvard)**Title:**A Recipe for π**Abstract:**In recognition of the upcoming “Pi Day, 2019,” we begin with a quick history of this illustrious constant, mentioning contributions from Archimedes, Newton, Leibniz, and Euler and carrying the story to the present day, where the value of π has been computed to trillions of places. Then, to add a bit of mathematics to the tale, we examine a result from Euler that features this constant in a starring role. In 1783, he sought the exact sum of the infinite seriestan(π⁄(4)+1/2tan(π⁄8)+1/4tan(π⁄(16)+1/8tan(π⁄(32)+...

His solution was devilishly clever in an 18th-century kind of way and should bring our celebration of π to a fitting end.

**Speaker:**John Mackey (Carnegie Mellon)**Title:**TBA**Abstract:**TBA

**Speaker:**Lauren Williams (Harvard)**Title:**TBA**Abstract:**TBA

**Speaker:**Alissa Crans (Loyola Marymount)**Title:**TBA**Abstract:**TBA

**Mailing list:** You can subscribe to the seminar mailing list here.

**Organizers:** Ana Balibanu (ana@math.harvard.edu) and Alison Miller (abmiller@math.harvard.edu)