# Events

Having run the Ross Mathematics Program online in Summer 2020, we will continue to build the online Ross community with some outreach events during the academic year. All these events will take place in our Zoom room, and are open to the broader mathematical community, so please feel free to invite your friends.

### QuaternionsProf. Daniel Shapiro

#### Thursday, October 08, 2020 at 7pm Eastern

The plane is represented as ordered pairs (a, b) of real numbers. By defining a multiplication operation on those pairs, we create the field đť—– of complex numbers. That multiplication can be viewed geometrically, yielding rotations and dilations of the plane. Many geometric problems can be recast as simpler statements within đť—–. In the 19th century, the complex numbers bacame a useful tool in studying problems of plane geometry.

In the 1840s, Hamilton hoped to find a similar algebraic structure underlying 3-dimensional space. After many failed attempts, he realized that the â€ścorrectâ€ť algebra is 4-dimensional. His system đť—› of quaternions has deep links with geometry in 3 and 4 dimensions. During the past 175 years, that 4-dimensional algebra has provided major motivations for subsequent work in algebra and geometry.

In this lecture we will discuss Hamiltonâ€™s ideas.

### Office hours, or Ask Me AnythingProf. Tim All

#### Wednesday, October 14, 2020 at 6pm Eastern

Join me for some informal office hours. We can discuss Ross problem sets, mathematics Iâ€™ve been thinking about and/or teaching recently, or anything else; digressions, diversions, and distractions are very welcome! Hope to see you there.

### ProofgrammingProf. Jim Fowler

#### Thursday, October 22, 2020 at 6pm Eastern

People use computers to help with computations, but can computers also help us write proofs? This talk is a friendly introduction to proof assistants, that is, to computer programs which help humans write proofs and verify their correctness.

The underlying machinery is â€śtype theoryâ€ť but rather than a survey, weâ€™ll see some examples. This is a â€śliveâ€ť talk in the sense that weâ€™ll see real examples running on a real computer, specifically using Agda. By the end, you will perhaps believe that writing proofs and writing programs are not so different after all.

### Games, Graphs, Groups, and Geometric SeriesProf. Rachel Skipper

#### Tuesday, October 27, 2020 at 6pm Eastern

In this talk, we will discuss the game â€śThe Towers of Hanoiâ€ť which comes from a legend about monks who have divine orders to move 64 golden disks among three pegs. The legend says that when the monks have moved the last disk, the world will end and asks the question: when? Weâ€™ll answer this question and see how the â€śHanoi Tower groupâ€ť connects the game to the Sierpinski triangle.