Failed networks, for example MPLS, can cause signaling storms the size of which can grow dramatically with network size. This paper presents a new scalable fault notification protocol that reduces the size of this storm. The protocol causes failure notification signals to travel vertically up and down a network hierarchy instead of horizontally along the service routes. This reduces the signali...

By using arithmetic circuits, encoding multivariate polynomials may be drastically more efficient than writing down the list of monomials. Via the study of two examples, we show however that such an encoding can be hard to handle with a Turing machine even if the degree of the polynomial is low. Namely we show that deciding whether the coefficient of a given monomial is zero is hard for P under...

The involvement of occipital cortex in sensory processing is not restricted solely to the visual modality. Tactile processing has been shown to modulate higher-order visual and multisensory integration areas in sighted as well as visually deprived subjects; however, the extent of involvement of early visual cortical areas remains unclear. To investigate this issue, we employed functional magnet...

How do we learn to recognize visual categories, such as dogs and cats? Somehow, the brain uses limited variable examples to extract the essential characteristics of new visual categories. Here, I describe an approach to category learning and recognition that is based on recent computational advances. In this approach, objects are represented by a hierarchy of fragments that are extracted during...

Understanding how peptides are selected for presentation by MHC class I is crucial to vaccination strategies based on cytotoxic T lymphocyte priming. We have studied this selection of the MHC class I peptide repertoire in terms of the presentation of a series of individual peptides with a wide range of binding to MHC class I. This series was expressed as minigenes, and the presentation of each ...

This paper presents a 3D object representation framework. We develop a hierarchical model based on probabilistic correspondences and probabilistic relations between 3D visual features. Features at the bottom of the hierarchy are bound to local observations. Pairs of features that present strong geometric correlation are iteratively grouped into higher-level meta-features that encode probabilist...

This paper presents a model in which resource allocations are calculated in real time by boundedly rational members of an administrative staff. We consider a class of hierarchical procedures in which information about payoff functions flows up and is aggregated by a hierarchy, while allocations flow down and are disaggregated by the hierarchy with decentralized decision making. We assume that t...

Motor sequences are formed through the serial execution of different movements, but how nervous systems implement this process remains largely unknown. We determined the organizational principles governing how dirty fruit flies groom their bodies with sequential movements. Using genetically targeted activation of neural subsets, we drove distinct motor programs that clean individual body parts....

Attributed tree transducers are abstract models used to study properties of attribute grammars. One abstraction which occurs when modeling attribute grammars by attributed tree transducers is that arbitrary trees over a ranked alphabet are taken as input, instead of derivation trees of a context-free grammar. In this paper we show that with respect to the generating power this is not an abstrac...