algebra

A tensor is a multi-way array of numbers. An order-1 tensor is just a vector $u \in \mathbb{R}^n$. An order-2 tensor is a matrix $M \in \mathbb{R}^{n_1 \times n_2}$. An order-3 tensor is a 3-way array $T \in \mathbb{R}^{n_1 \times n_2 \times n_3}$, and so on.

Informally, a mechanical linkage is a system of rigid links (rods or bars) connected by ideal joints and moving in the plane or in the space. This definition suffices for engineering purposes, and one can find it in some form in many engineering books. However, from the mathematical viewpoint, this is not a satisfactory definition.

Melissa Zhang is a low-dimensional topologist who likes to use algebraic, combinatorial, and categorical methods to solve problems. Her favorite topological objects are knots and surfaces smoothly embedded in 3- and 4-dimensional spaces.

She received her Ph.D. from Boston College under the supervision of Eli Grigsby and David Treumann. She was previously a postdoc at the University of Georgia, SLMath/MSRI, and UC Davis (and is now a super-postdoc, as she never left).

David G. Mead passed away on September 19, 2016, at the age of 94. 

He began study at Columbia University in New York, but delayed his degree with the start of World War II. He served as a sergeant in the US Army in the Pacific theater. When David returned after his honorable discharge in 1946, he earned his Ph.D. in 1959 with the dissertation Linear and Nonlinear Differential Polynomials. He met his wife, Alba Saba, while at Columbia, and began his teaching career there.