Unprojection or "constructing bigger Gorenstein ideals from smaller one" is an algebraic device for constructing Gorenstein varieties in codimension 4, 5, ..., beyond the range of standard structure theorems; it has a large number of fairly ...

Volume entropy of a compact manifold is the exponential growth rate of balls in the universal cover. This seemingly coarse invariant contains a lot of geometric information of the manifold. We will discuss some relations to other invariants,...