I'll describe an interacting holomorphic-topological field theory in eleven dimensions defined on products of Calabi-Yau 5-folds with real one-manifolds. The theory describes a certain deformation of the cotangent bundle to the moduli of Calabi-Yau deformations of the 5-fold and conjecturally describes a certain protected sector of eleven-dimensional supergravity. Strikingly, the theory has an infinite dimensional global symmetry algebra given by an extension of the exceptional lie superalgebra E(5,10) first studied by Kac. This talk is based on joint work with Ingmar Saberi and Brian Williams.

Computers have been used to process natural language for many years. This talk considers two historical examples of computers used rather to play with human language, one well-known and the other a new archival discovery: Strachey’s 1952 love letters program, and a poetry programming competition held at Newcastle University in 1968. Strachey’s program used random number generation to pick words to fit into a template, resulting in letters of varying quality, and apparently much amusement for Strachey. The poetry competition required the entrants, mostly PhD students, to write programs whose output or source code was in some way poetic: the entries displayed remarkable ingenuity. Various analyses of Strachey’s work depict it as a parody of attitudes to love, an artistic endeavour, or as a technical exploration. In this talk I will consider how these apply to the Newcastle competition and add my own interpretations.

We tie together two natural but, a priori, different themes. As a starting point consider Erdős and Simonovits's classical edge stability for an $(r + 1)$-chromatic graph $H$. This says that any $n$-vertex $H$-free graph with $(1 − 1/r + o(1)){n \choose 2}$ edges is close to (within $o(n^2)$ edges of) $r$-partite. This is false if $1 − 1/r$ is replaced by any smaller constant. However, instead of insisting on many edges, what if we ask that the $n$-vertex graph has large minimum degree? This is the basic question of minimum degree stability: what constant $c$ guarantees that any $n$-vertex $H$-free graph with minimum degree greater than $cn$ is close to $r$-partite? $c$ depends not just on chromatic number of $H$ but also on its finer structure.

Somewhat surprisingly, answering the minimum degree stability question requires understanding locally colourable graphs -- graphs in which every neighbourhood has small chromatic number -- with large minimum degree. This is a natural local-to-global colouring question: if every neighbourhood is big and has small chromatic number must the whole graph have small chromatic number? The triangle-free case has a rich history. The more general case has some similarities but also striking differences.