Multivariate Hawkes Processes for Large-scale Inference

In this paper, we present a framework for fitting multivariate Hawkes processes for large-scale problems both in the number of events in the observed history $n$ and the number of event types $d$ (i.e. dimensions). The proposed Low-Rank Hawkes Process (LRHP) framework introduces a low-rank approximation of the kernel matrix that allows to perform the nonparametric learning of the $d^2$ triggering kernels using at most $O(ndr^2)$ operations, where $r$ is the rank of the approximation ($r \ll d,n$). This comes as a major improvement to the existing state-of-the-art inference algorithms that are in $O(nd^2)$. Furthermore, the low-rank approximation allows LRHP to learn representative patterns of interaction between event types, which may be valuable for the analysis of such complex processes in real world datasets. The efficiency and scalability of our approach is illustrated with numerical experiments on simulated as well as real datasets.Comment: 16 pages, 5 figure

Technology

The paper summarizes recent break-through in the anthropology of material culture, objects, techniques. It explains the main fields of the discipline and its evolution. A large section is about examples of field study in Papua New Guinea. Another one exposes the basic field methods to collect ethnographical data in cultural technology

Auto-anthropology, Modernity and Automobiles

Pour les collectionneurs d'automobiles "classiques", ces voiture et leurs modèles réduits fonctionnent comme des résonateurs mêlant dans l'esprit de l'acteur divers aspects de la culture automobile d'une façon qui participe à la production d'un imaginaire partagé

Fangio, Rozanoff et l'Espadon. A propos d'objets et d'imaginaires partagés

Anthropologie et histoire des rapports des baby-boomers avec les automobiles, notamment de compétition. Dimension cognitive des pratiques matérielles et mémorielles

Arcs, flèches et orgue électrique. A propos de modernité et d'offensives évangéliques dans la vallée de Wonenara (Papouasie Nouvelle-Guinée)

International audienceL'avancée des églises évangéliques dans la lointaine vallée de Wonenara (Papouasie) est incompréhensible hors du contexte historique des événements qui ont suivi le premier contact avec cette population, en 1951: transformation des initiations masculines, paix forcés avec les groupes voisins, présence ancienne des Luthériens, modernité et économie du café

On the structure of framed vertex operator algebras and their pointwise frame stabilizers

In this paper, we study the structure of a general framed vertex operator algebra. We show that the structure codes (C,D) of a framed VOA V satisfy certain duality conditions. As a consequence, we prove that every framed VOA is a simple current extension of the associated binary code VOA V_C. This result would give a prospect on the classification of framed vertex operator algebras. In addition, the pointwise frame stabilizer of V is studied. We completely determine all automorphisms in this pointwise stabilizer, which are of order 1, 2 or 4. The 4A-twisted sector and the 4A-twisted orbifold theory of the famous Moonshine VOA are also constructed explicitly. We verify that the top module of this twisted sector is of dimension 1 and of weight 3/4 and the VOA obtained by 4A-twisted orbifold construction of the moonshine VOA is isomorphic to the moonshine VOA itself.Comment: Version 3: 59 pages. Corrected version. 54 pages on my LaTeX system version 2: We add Theorem 5.16 in which we give a necessary and sufficient condtion for a code to be a structure code of a holomorphic framed VOA. "hyperref" style is also introduce