Class field theory for arithmetic schemes

Let X be a regular arithmetic scheme, i.e. a regular integral separated scheme flat and of finite type over Spec . Generalising classical class field theory for number fields, we define a class group C _X and show there is a natural surjective map whose kernel is the connected component of 0.      

Non-abelian GKM theory

We describe a generalization of GKM theory for actions of arbitrary compact connected Lie groups. To an action satisfying the non-abelian GKM conditions we attach a graph encoding the structure of the non-abelian 1-skeleton, i.e., the subspace of points with isotopy rank at most one less than the rank of the acting group. We show that the algebra structure of the equivariant cohomology can be read off from this graph. In comparison with ordinary abelian GKM theory, there are some special features due to the more complicated structure of the non-abelian 1-skeleton.     

Line bundles on arithmetic surfaces and intersection theory

For line bundles on arithmetic varieties we construct height functions using arithmetic intersection theory. In the case of an arithmetic surface, generically of genusg, for line bundles of degreeg equivalence is shown to the height on the Jacobian defined by Θ. We recover the classical formula due to Faltings and Hriljac for the Néron-Tate height on the Jacobian in terms of the intersection pairing on the arithmetic surface.     

Valuations on arithmetic surfaces

In this paper, we give the definition of the height of a valuation and the definition of the big field Cp,G, where p is a prime and GR is an additive subgroup containing 1. We conclude that Cp,G is a field and Cp,G is algebraically closed. Based on this the author obtains the complete classification of valuations on arithmetic surfaces. Furthermore, for any m ≤n∈ Z, let Vm,n be an R-vector space of dimension n-m + 1, whose coordinates are indexed from m to n. We generalize the definition of Cp,G, where p i...     

On pluri-canonical systems of arithmetic surfaces

Let \({S}\) be a Dedekind scheme with perfect residue fields at closed points. Let \({f: X\rightarrow S}\) be a minimal regular arithmetic surface of fibre genus at least 2 and let \({f': X'\rightarrow S}\) be the canonical model of \({f}\). It is well known that \({\omega_{X'/S}}\) is relatively ample. In this paper we prove that \({\omega_{X'/S}^{\otimes n}}\) is relatively very ample for all \({n\geq 3}\).     

Higher class field theory and the connected component

In this note we present a new self-contained approach to the class field theory of arithmetic schemes in the sense of Wiesend. Along the way we prove new results on space filling curves on arithmetic schemes and on the class field theory of local rings. We show how one can deduce the more classical version of higher global class field theory due to Kato and Saito from Wiesend??s version. One of our new results says that the connected component of the identity element in Wiesend??s class group is divisible if some obstruction is absent.     

Covering data and higher dimensional global class field theory

For a connected regular scheme X, flat and of finite type over Spec(Z), we construct a reciprocity homomorphism , which is surjective and whose kernel is the connected component of the identity. The (topological) group CX is explicitly given and built solely out of data attached to points and curves on X. A similar but weaker statement holds for smooth varieties over finite fields. Our results are based on earlier work of G. Wiesend.     

Hurwitz quaternion order and arithmetic Riemann surfaces

We clarify the explicit structure of the Hurwitz quaternion order, which is of fundamental importance in Riemann surface theory and systolic geometry.