This proposal concerns the relation between two different areas of algebra: group theory, the abstract study of symmetry, and algebraic number theory, the study of algebraic numbers, like the square root of 2 (as opposed to transcendental numbers, like pi). The main link between these two fields is provided by algebraic geometry, the geometry of systems of polynomial equations in several variables. A key theme in the proposed work is monodromy, which encapsulates the symmetries revealed by a parametrized system as the parameter follows a closed loop. Monodromy problems arise in many settings, in both pure and applied mathematics. For instance some of the techniques under study in this proposal have been used by the proposer and others to determine which kinds of computations can be carried out by different kinds of quantum computer. Algebraic number theory has found important practical applications, especially in the development of modern cryptosystems.
The theme of this proposal is group theory in relation to algebraic number theory. The main goal is to use group theory as a tool, for instance in analyzing images of l-adic Galois representations, or Mordell-Weil groups of abelian varieties over Galois extensions of the rationals. The secondary goal is to study groups, especially linear groups, using methods from number theory and algebraic geometry, including the circle method, etale cohomology, and deformation theory.
