We apply the Hecke operators T (p) and T ′ j (p) (1 ≤ j ≤ n ≤ 2k) to a degree n theta series attached to a rank 2k Z-lattice L equipped with a positive definite quadratic form in the case that L/pL is regular. We explicitly realize the image of the theta series under these Hecke operators as a sum of theta series attached to certain sublattices of 1 p L, thereby generalizing the Eichler Commuta...

Let π : X → T be a deformation of a normal Gorenstein surface singularity over the complex number field C. We assume that T is a neighborhood of the origin of C. Then we prove that π admits a simultaneous log-canonical model if and only if an invariant −Pt · Pt of each fiber Xt is constant.

We study 2-monads and their algebras using a Cat-enriched version of Quillen model categories, emphasizing the parallels between the homotopical and 2-categorical points of view. Every 2-category with finite limits and colimits has a canonical model structure in which the weak equivalences are the equivalences; we use these to construct more interesting model structures on 2-categories, includi...

Diversity is an asset, as long as it allows cooperation. In the case of information systems and databases, the data model used is a help or a hindrance for this cooperation of diverse views; this is characterized by the semantic relativism of the model. We first analyze diversity within an information system, where cooperation is made possible by the use of external schemata; semantic relativis...

One of the key issues in the computational representation of open societies relates to the introduction of norms that help to cope with the heterogeneity, the autonomy and the diversity of interests among their members. Research regarding this issue presents two omissions. One is the lack of a canonical model of norms that facilitates their implementation, and that allows us to describe the pro...

We apply the Hecke operators T (p) and T̃j(p 2) (1 ≤ j ≤ n, p prime) to a degree n theta series attached to a rank 2k Z-lattice L, n ≤ k, equipped with a positive definite quadratic form in the case that L/pL is hyperbolic. We show that the image of the theta series under these Hecke operators can be realized as a sum of theta series attached to certain closely related lattices, thereby generali...

We explain, in the case of good reduction, the conjecture of Langlands and Rapoport describing the structure of the points on the reduction of a Shimura variety (Langlands and Rapoport 1987, 5.e, p169), and we derive from it the formula conjectured in (Kottwitz 1990, 3.1), which expresses a certain trace as a sum of products of (twisted) orbital integrals. Also we introduce the notion of an int...

Wildeshaus and others have pointed out to me that it is not obvious that the descent maps on a Shimura variety given by Langlands’s Conjugacy Conjecture (Langlands 1979, Section 6) satisfy the continuity condition required for the descent to be effective. The following provides one proof of this (maybe not the best). Since the family (fσ) satisfying the conditions (a,b,c) below is unique (by th...

We develop the homotopy theory of Euler characteristic (magnitude) of a category enriched in a monoidal model category. If a monoidal model category V is equipped with an Euler characteristic that is compatible with weak equivalences and fibrations in V, then our Euler characteristic of V-enriched categories is also compatible with weak equivalences and fibrations in the canonical model structu...