373 research outputs found
Budgeted Knowledge Transfer for State-wise Heterogeneous RL Agents
In this paper we introduce a budgeted knowledge transfer algorithm for non-homogeneous reinforcement learning agents. Here the source and the target agents are completely identical except in their state representations. The algorithm uses functional space (Q-value space) as the transfer-learning media. In this method, the target agent’s functional points (Q-values) are estimated in an automatically selected lower-dimension subspace in order to accelerate knowledge transfer. The target agent searches that subspace using an exploration policy and selects actions accordingly during the period of its knowledge transfer in order to facilitate gaining an appropriate estimate of its Q-table. We show both analytically and empirically that this method decreases the required learning budget for the target agent
Advances in Intelligent Vehicle Control
This book is a printed edition of the Special Issue Advances in Intelligent Vehicle Control that was published in the journal Sensors. It presents a collection of eleven papers that covers a range of topics, such as the development of intelligent control algorithms for active safety systems, smart sensors, and intelligent and efficient driving. The contributions presented in these papers can serve as useful tools for researchers who are interested in new vehicle technology and in the improvement of vehicle control systems
Adversarial jamming attacks and defense strategies via adaptive deep reinforcement learning
As the applications of deep reinforcement learning (DRL) in wireless
communications grow, sensitivity of DRL based wireless communication strategies
against adversarial attacks has started to draw increasing attention. In order
to address such sensitivity and alleviate the resulting security concerns, we
in this paper consider a victim user that performs DRL-based dynamic channel
access, and an attacker that executes DRLbased jamming attacks to disrupt the
victim. Hence, both the victim and attacker are DRL agents and can interact
with each other, retrain their models, and adapt to opponents' policies. In
this setting, we initially develop an adversarial jamming attack policy that
aims at minimizing the accuracy of victim's decision making on dynamic channel
access. Subsequently, we devise defense strategies against such an attacker,
and propose three defense strategies, namely diversified defense with
proportional-integral-derivative (PID) control, diversified defense with an
imitation attacker, and defense via orthogonal policies. We design these
strategies to maximize the attacked victim's accuracy and evaluate their
performances.Comment: 13 pages, 24 figure
Decision-Making with Multi-Step Expert Advice on the Web
This thesis deals with solving multi-step tasks by using advice from experts, which are algorithms to solve individual steps of such tasks. We contribute with methods for maximizing the number of correct task solutions by selecting and combining experts for individual task instances and methods for automating the process of solving tasks on the Web, where experts are available as Web services.
Multi-step tasks frequently occur in Natural Language Processing (NLP) or Computer Vision, and as research progresses an increasing amount of exchangeable experts for the same steps are available on the Web. Service provider platforms such as Algorithmia monetize expert access by making expert services available via their platform and having customers pay for single executions.
Such experts can be used to solve diverse tasks, which often consist of multiple steps and thus require pipelines of experts to generate hypotheses.
We perceive two distinct problems for solving multi-step tasks with expert services: (1) Given that the task is sufficiently complex, no single pipeline generates correct solutions for all possible task instances. One thus must learn how to construct individual expert pipelines for individual task instances in order to maximize the number of correct solutions, while also taking into account the costs adhered to executing an expert. (2) To automatically solve multi-step tasks with expert services, we need to discover, execute and compose expert pipelines. With mostly textual descriptions of complex functionalities and input parameters, Web automation entails to integrate available expert services and data, interpreting user-specified task goals or efficiently finding correct service configurations.
In this thesis, we present solutions to both problems: (1) We enable to learn well-performing expert pipelines assuming available reference data sets (comprising a number of task instances and solutions), where we distinguish between centralized and decentralized decision-making. We formalize the problem as specialization of a Markov Decision Process (MDP), which we refer to as Expert Process (EP) and integrate techniques from Statistical Relational Learning (SRL) or Multiagent coordination. (2) We develop a framework for automatically discovering, executing and composing expert pipelines by exploiting methods developed for the Semantic Web. We lift the representations of experts with structured vocabularies modeled with the Resource Description Framework (RDF) and extend EPs to Semantic Expert Processes (SEPs) to enable the data-driven execution of experts in Web-based architectures.
We evaluate our methods in different domains, namely Medical Assistance with tasks in Image Processing and Surgical Phase Recognition, and NLP for textual data on the Web, where we deal with the task of Named Entity Recognition and Disambiguation (NERD)
Active Learning for Reducing Labeling Effort in Text Classification Tasks
Labeling data can be an expensive task as it is usually performed manually by
domain experts. This is cumbersome for deep learning, as it is dependent on
large labeled datasets. Active learning (AL) is a paradigm that aims to reduce
labeling effort by only using the data which the used model deems most
informative. Little research has been done on AL in a text classification
setting and next to none has involved the more recent, state-of-the-art Natural
Language Processing (NLP) models. Here, we present an empirical study that
compares different uncertainty-based algorithms with BERT as the used
classifier. We evaluate the algorithms on two NLP classification datasets:
Stanford Sentiment Treebank and KvK-Frontpages. Additionally, we explore
heuristics that aim to solve presupposed problems of uncertainty-based AL;
namely, that it is unscalable and that it is prone to selecting outliers.
Furthermore, we explore the influence of the query-pool size on the performance
of AL. Whereas it was found that the proposed heuristics for AL did not improve
performance of AL; our results show that using uncertainty-based AL with
BERT outperforms random sampling of data. This difference in
performance can decrease as the query-pool size gets larger.Comment: Accepted as a conference paper at the joint 33rd Benelux Conference
on Artificial Intelligence and the 30th Belgian Dutch Conference on Machine
Learning (BNAIC/BENELEARN 2021). This camera-ready version submitted to
BNAIC/BENELEARN, adds several improvements including a more thorough
discussion of related work plus an extended discussion section. 28 pages
including references and appendice
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