6,306 research outputs found
End-to-End Reinforcement Learning for Automatic Taxonomy Induction
We present a novel end-to-end reinforcement learning approach to automatic
taxonomy induction from a set of terms. While prior methods treat the problem
as a two-phase task (i.e., detecting hypernymy pairs followed by organizing
these pairs into a tree-structured hierarchy), we argue that such two-phase
methods may suffer from error propagation, and cannot effectively optimize
metrics that capture the holistic structure of a taxonomy. In our approach, the
representations of term pairs are learned using multiple sources of information
and used to determine \textit{which} term to select and \textit{where} to place
it on the taxonomy via a policy network. All components are trained in an
end-to-end manner with cumulative rewards, measured by a holistic tree metric
over the training taxonomies. Experiments on two public datasets of different
domains show that our approach outperforms prior state-of-the-art taxonomy
induction methods up to 19.6\% on ancestor F1.Comment: 11 Pages. ACL 2018 Camera Read
-Learning: A Collaborative Distributed Strategy for Multi-Agent Reinforcement Learning Through Consensus + Innovations
The paper considers a class of multi-agent Markov decision processes (MDPs),
in which the network agents respond differently (as manifested by the
instantaneous one-stage random costs) to a global controlled state and the
control actions of a remote controller. The paper investigates a distributed
reinforcement learning setup with no prior information on the global state
transition and local agent cost statistics. Specifically, with the agents'
objective consisting of minimizing a network-averaged infinite horizon
discounted cost, the paper proposes a distributed version of -learning,
-learning, in which the network agents collaborate by means of
local processing and mutual information exchange over a sparse (possibly
stochastic) communication network to achieve the network goal. Under the
assumption that each agent is only aware of its local online cost data and the
inter-agent communication network is \emph{weakly} connected, the proposed
distributed scheme is almost surely (a.s.) shown to yield asymptotically the
desired value function and the optimal stationary control policy at each
network agent. The analytical techniques developed in the paper to address the
mixed time-scale stochastic dynamics of the \emph{consensus + innovations}
form, which arise as a result of the proposed interactive distributed scheme,
are of independent interest.Comment: Submitted to the IEEE Transactions on Signal Processing, 33 page
Modular Design Patterns for Hybrid Learning and Reasoning Systems: a taxonomy, patterns and use cases
The unification of statistical (data-driven) and symbolic (knowledge-driven)
methods is widely recognised as one of the key challenges of modern AI. Recent
years have seen large number of publications on such hybrid neuro-symbolic AI
systems. That rapidly growing literature is highly diverse and mostly
empirical, and is lacking a unifying view of the large variety of these hybrid
systems. In this paper we analyse a large body of recent literature and we
propose a set of modular design patterns for such hybrid, neuro-symbolic
systems. We are able to describe the architecture of a very large number of
hybrid systems by composing only a small set of elementary patterns as building
blocks.
The main contributions of this paper are: 1) a taxonomically organised
vocabulary to describe both processes and data structures used in hybrid
systems; 2) a set of 15+ design patterns for hybrid AI systems, organised in a
set of elementary patterns and a set of compositional patterns; 3) an
application of these design patterns in two realistic use-cases for hybrid AI
systems. Our patterns reveal similarities between systems that were not
recognised until now. Finally, our design patterns extend and refine Kautz'
earlier attempt at categorising neuro-symbolic architectures.Comment: 20 pages, 22 figures, accepted for publication in the International
Journal of Applied Intelligenc
Depressive statements prime goal-directed alcohol-seeking in individuals who report drinking to cope with negative affect
This is the author accepted manuscript. The final version is available from Springer Verlag via the DOI in this record.Background Most variants of negative reinforcement theory predict that acute depressed
mood can promote alcohol-seeking behaviour, but the precise mechanisms underpinning this
effect remain contested. One possibility is that mood-induced alcohol-seeking is due to the
formation of a stimulus-response (S-R) association, enabling depressed mood to elicit
alcohol-seeking automatically. A second possibility is that depressed mood undergoes
incentive learning, enabling it to enhance the expected value of alcohol and thus promote
goal-directed alcohol-seeking. Objectives These two explanations were distinguished using a
human outcome-revaluation procedure. Methods One hundred and twenty eight alcohol
drinkers completed questionnaires of alcohol use disorder, drinking to cope with negative
affect and depression symptoms. Participants then learned that two responses earned alcohol
and food points respectively (baseline) in two-alternative forced-choice trials. At test,
participants rated the valence of randomly sampled negative and positive mood statements
and, after each statement, chose between the alcohol- or food-seeking response in extinction.
Results The percentage of alcohol- vs. food-seeking responses was increased significantly in
trials containing negative statements compared to baseline and positive statement trials, in
individuals who reported drinking to cope with negative affect (p=.004), but there was no
such interaction with indices of alcohol use disorder (p=.87) or depression symptoms (p=.58).
Conclusions: Individuals who drink to cope with negative affect are more sensitive to the
motivational impact of acute depressed mood statements priming goal-directed alcoholseeking.
Negative copers’ vulnerability to alcohol dependence may be better explained by
excessive affective incentive learning than by S-R habit formation.The work was supported by the ESRC and Alcohol Research UK
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