876 research outputs found
Deep Tree Transductions - A Short Survey
The paper surveys recent extensions of the Long-Short Term Memory networks to
handle tree structures from the perspective of learning non-trivial forms of
isomorph structured transductions. It provides a discussion of modern TreeLSTM
models, showing the effect of the bias induced by the direction of tree
processing. An empirical analysis is performed on real-world benchmarks,
highlighting how there is no single model adequate to effectively approach all
transduction problems.Comment: To appear in the Proceedings of the 2019 INNS Big Data and Deep
Learning (INNSBDDL 2019). arXiv admin note: text overlap with
arXiv:1809.0909
Learning Tree Distributions by Hidden Markov Models
Hidden tree Markov models allow learning distributions for tree structured
data while being interpretable as nondeterministic automata. We provide a
concise summary of the main approaches in literature, focusing in particular on
the causality assumptions introduced by the choice of a specific tree visit
direction. We will then sketch a novel non-parametric generalization of the
bottom-up hidden tree Markov model with its interpretation as a
nondeterministic tree automaton with infinite states.Comment: Accepted in LearnAut2018 worksho
Detecting Adversarial Examples through Nonlinear Dimensionality Reduction
Deep neural networks are vulnerable to adversarial examples, i.e.,
carefully-perturbed inputs aimed to mislead classification. This work proposes
a detection method based on combining non-linear dimensionality reduction and
density estimation techniques. Our empirical findings show that the proposed
approach is able to effectively detect adversarial examples crafted by
non-adaptive attackers, i.e., not specifically tuned to bypass the detection
method. Given our promising results, we plan to extend our analysis to adaptive
attackers in future work.Comment: European Symposium on Artificial Neural Networks, Computational
Intelligence and Machine Learning (ESANN) 201
DropIn: Making Reservoir Computing Neural Networks Robust to Missing Inputs by Dropout
The paper presents a novel, principled approach to train recurrent neural
networks from the Reservoir Computing family that are robust to missing part of
the input features at prediction time. By building on the ensembling properties
of Dropout regularization, we propose a methodology, named DropIn, which
efficiently trains a neural model as a committee machine of subnetworks, each
capable of predicting with a subset of the original input features. We discuss
the application of the DropIn methodology in the context of Reservoir Computing
models and targeting applications characterized by input sources that are
unreliable or prone to be disconnected, such as in pervasive wireless sensor
networks and ambient intelligence. We provide an experimental assessment using
real-world data from such application domains, showing how the Dropin
methodology allows to maintain predictive performances comparable to those of a
model without missing features, even when 20\%-50\% of the inputs are not
available
Using a Machine Learning Approach to Implement and Evaluate Product Line Features
Bike-sharing systems are a means of smart transportation in urban
environments with the benefit of a positive impact on urban mobility. In this
paper we are interested in studying and modeling the behavior of features that
permit the end user to access, with her/his web browser, the status of the
Bike-Sharing system. In particular, we address features able to make a
prediction on the system state. We propose to use a machine learning approach
to analyze usage patterns and learn computational models of such features from
logs of system usage.
On the one hand, machine learning methodologies provide a powerful and
general means to implement a wide choice of predictive features. On the other
hand, trained machine learning models are provided with a measure of predictive
performance that can be used as a metric to assess the cost-performance
trade-off of the feature. This provides a principled way to assess the runtime
behavior of different components before putting them into operation.Comment: In Proceedings WWV 2015, arXiv:1508.0338
Linear Memory Networks
Recurrent neural networks can learn complex transduction problems that
require maintaining and actively exploiting a memory of their inputs. Such
models traditionally consider memory and input-output functionalities
indissolubly entangled. We introduce a novel recurrent architecture based on
the conceptual separation between the functional input-output transformation
and the memory mechanism, showing how they can be implemented through different
neural components. By building on such conceptualization, we introduce the
Linear Memory Network, a recurrent model comprising a feedforward neural
network, realizing the non-linear functional transformation, and a linear
autoencoder for sequences, implementing the memory component. The resulting
architecture can be efficiently trained by building on closed-form solutions to
linear optimization problems. Further, by exploiting equivalence results
between feedforward and recurrent neural networks we devise a pretraining
schema for the proposed architecture. Experiments on polyphonic music datasets
show competitive results against gated recurrent networks and other state of
the art models
Realizzazione di algoritmi con calibrazione in tempo reale per il riconoscimento di posture della mano mediante tessuto sensorizzato.
Questo lavoro consiste nella realizzazione e sperimentazione di algoritmi di calibrazione in tempo reale per un sistema indossabile, con lo specifico obiettivo di riconoscere un insieme discreto di posture della mano. In particolare, il sistema è stato sviluppato per il guanto in tessuto sensorizzato creato nei laboratori del Centro E. Piaggio dell'Università di Pisa
Unsupervised feature selection for sensor time-series in pervasive computing applications
The paper introduces an efficient feature selection approach for multivariate time-series of heterogeneous sensor data within a pervasive computing scenario. An iterative filtering procedure is devised to reduce information redundancy measured in terms of time-series cross-correlation. The algorithm is capable of identifying nonredundant sensor sources in an unsupervised fashion even in presence of a large proportion of noisy features. In particular, the proposed feature selection process does not require expert intervention to determine the number of selected features, which is a key advancement with respect to time-series filters in the literature. The characteristic of the prosed algorithm allows enriching learning systems, in pervasive computing applications, with a fully automatized feature selection mechanism which can be triggered and performed at run time during system operation. A comparative experimental analysis on real-world data from three pervasive computing applications is provided, showing that the algorithm addresses major limitations of unsupervised filters in the literature when dealing with sensor time-series. Specifically, it is presented an assessment both in terms of reduction of time-series redundancy and in terms of preservation of informative features with respect to associated supervised learning tasks
Concentric ESN: Assessing the Effect of Modularity in Cycle Reservoirs
The paper introduces concentric Echo State Network, an approach to design
reservoir topologies that tries to bridge the gap between deterministically
constructed simple cycle models and deep reservoir computing approaches. We
show how to modularize the reservoir into simple unidirectional and concentric
cycles with pairwise bidirectional jump connections between adjacent loops. We
provide a preliminary experimental assessment showing how concentric reservoirs
yield to superior predictive accuracy and memory capacity with respect to
single cycle reservoirs and deep reservoir models
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