1,881,986 research outputs found
A Note on Parameterised Knowledge Operations in Temporal Logic
We consider modeling the conception of knowledge in terms of temporal logic.
The study of knowledge logical operations is originated around 1962 by
representation of knowledge and belief using modalities. Nowadays, it is very
good established area. However, we would like to look to it from a bit another
point of view, our paper models knowledge in terms of linear temporal logic
with {\em past}. We consider various versions of logical knowledge operations
which may be defined in this framework. Technically, semantics, language and
temporal knowledge logics based on our approach are constructed. Deciding
algorithms are suggested, unification in terms of this approach is commented.
This paper does not offer strong new technical outputs, instead we suggest new
approach to conception of knowledge (in terms of time).Comment: 10 page
Detecting the community structure and activity patterns of temporal networks: a non-negative tensor factorization approach
The increasing availability of temporal network data is calling for more
research on extracting and characterizing mesoscopic structures in temporal
networks and on relating such structure to specific functions or properties of
the system. An outstanding challenge is the extension of the results achieved
for static networks to time-varying networks, where the topological structure
of the system and the temporal activity patterns of its components are
intertwined. Here we investigate the use of a latent factor decomposition
technique, non-negative tensor factorization, to extract the community-activity
structure of temporal networks. The method is intrinsically temporal and allows
to simultaneously identify communities and to track their activity over time.
We represent the time-varying adjacency matrix of a temporal network as a
three-way tensor and approximate this tensor as a sum of terms that can be
interpreted as communities of nodes with an associated activity time series. We
summarize known computational techniques for tensor decomposition and discuss
some quality metrics that can be used to tune the complexity of the factorized
representation. We subsequently apply tensor factorization to a temporal
network for which a ground truth is available for both the community structure
and the temporal activity patterns. The data we use describe the social
interactions of students in a school, the associations between students and
school classes, and the spatio-temporal trajectories of students over time. We
show that non-negative tensor factorization is capable of recovering the class
structure with high accuracy. In particular, the extracted tensor components
can be validated either as known school classes, or in terms of correlated
activity patterns, i.e., of spatial and temporal coincidences that are
determined by the known school activity schedule
CLARITY at the TREC 2011 microblog track
For the first year of the TREC Microblog Track the CLARITY group concentrated on a number of areas, investigating the underlying term weighting scheme for ranking tweets, incorporating query expansion to introduce new terms into the query, as well as introducing an element of temporal re-weighting based on the temporal distribution of assumed relevant microblogs
Stable Electromyographic Sequence Prediction During Movement Transitions using Temporal Convolutional Networks
Transient muscle movements influence the temporal structure of myoelectric
signal patterns, often leading to unstable prediction behavior from
movement-pattern classification methods. We show that temporal convolutional
network sequential models leverage the myoelectric signal's history to discover
contextual temporal features that aid in correctly predicting movement
intentions, especially during interclass transitions. We demonstrate
myoelectric classification using temporal convolutional networks to effect 3
simultaneous hand and wrist degrees-of-freedom in an experiment involving nine
human-subjects. Temporal convolutional networks yield significant
performance improvements over other state-of-the-art methods in terms of both
classification accuracy and stability.Comment: 4 pages, 5 figures, accepted for Neural Engineering (NER) 2019
Conferenc
Bayesian joint spatio-temporal analysis of multiple diseases
In this paper we propose a Bayesian hierarchical spatio-temporal model for the joint analysis of multiple diseases which includes specific and shared spatial and temporal effects. Dependence on shared terms is controlled by disease-specific weights so that their posterior distribution can be used to identify diseases with similar spatial and temporal patterns. The model proposed here has been used to study three different causes of death (oral cavity, esophagus and stomach cancer) in Spain at the province level. Shared and specific spatial and temporal effects have been estimated and mapped in order to study similarities and differences among these causes. Furthermore, estimates using Markov chain Monte Carlo and the integrated nested Laplace approximation are compared.Peer Reviewe
Gauge-invariant quark and gluon fields in QCD: dynamics, topology, and the Gribov ambiguity
We review the implementation, in a temporal-gauge formulation of QCD, of the
non-Abelian Gauss's law and the construction of gauge-invariant gauge and
matter fields. We then express the QCD Hamiltonian in terms of these
gauge-invariant operator-valued fields, and discuss the relation of this
Hamiltonian and the gauge-invariant fields to the corresponding quantities in a
Coulomb gauge formulation of QCD. We argue that a representation of QCD in
terms of gauge-invariant quantities could be particularly useful for
understanding low-energy phenomenology. We present the results of an
investigation into the topological properties of the gauge-invariant fields,
and show that there are Gribov copies of these gauge-invariant gauge fields,
which are constructed in the temporal gauge, even though the conditions that
give rise to Gribov copies do not obtain for the gauge-dependent temporal-gauge
fields.Comment: 5 pages LaTex; talk presented at light-cone workshop "Particles and
Strings", Trento, Italy, September 200
What can we learn about Gribov copies from a formulation of QCD in terms of gauge-invariant fields?
We review the procedure by which we implemented the non-Abelian Gauss's law
and constructed gauge-invariant fields for QCD in the temporal (Weyl) gauge. We
point out that the operator-valued transformation that transforms
gauge-dependent temporal-gauge fields into gauge-invariant ones has the formal
structure of a gauge transformation. We express the ``standard'' Hamiltonian
for temporal-gauge QCD entirely in terms of gauge-invariant fields, calculate
the commutation rules for these fields, and compare them to earlier work on
Coulomb-gauge QCD. We also discuss multiplicities of gauge-invariant
temporal-gauge fields that belong to different topological sectors and that, in
previous work, were shown to be based on the same underlying gauge-dependent
temporal-gauge fields. We relate these multiplicities of gauge-invariant fields
to Gribov copies. We argue that Gribov copies appear in the temporal gauge, but
not when the theory is represented in terms of gauge-dependent fields and
Gauss's law is left unimplemented. There are Gribov copies of the
gauge-invariant gauge field, which can be constructed when Gauss's law is
implemented.Comment: To appear in Proceedings of the 6th Workshop on Non-Perturbative QCD,
Paris, France, June 5-9, 200
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