Goto

Collaborating Authors

 Markov Models


Developing A Multi-Agent and Self-Adaptive Framework with Deep Reinforcement Learning for Dynamic Portfolio Risk Management

arXiv.org Artificial Intelligence

Deep or reinforcement learning (RL) approaches have been adapted as reactive agents to quickly learn and respond with new investment strategies for portfolio management under the highly turbulent financial market environments in recent years. In many cases, due to the very complex correlations among various financial sectors, and the fluctuating trends in different financial markets, a deep or reinforcement learning based agent can be biased in maximising the total returns of the newly formulated investment portfolio while neglecting its potential risks under the turmoil of various market conditions in the global or regional sectors. Accordingly, a multi-agent and self-adaptive framework namely the MASA is proposed in which a sophisticated multi-agent reinforcement learning (RL) approach is adopted through two cooperating and reactive agents to carefully and dynamically balance the trade-off between the overall portfolio returns and their potential risks. Besides, a very flexible and proactive agent as the market observer is integrated into the MASA framework to provide some additional information on the estimated market trends as valuable feedbacks for multi-agent RL approach to quickly adapt to the ever-changing market conditions. The obtained empirical results clearly reveal the potential strengths of our proposed MASA framework based on the multi-agent RL approach against many well-known RL-based approaches on the challenging data sets of the CSI 300, Dow Jones Industrial Average and S&P 500 indexes over the past 10 years. More importantly, our proposed MASA framework shed lights on many possible directions for future investigation.


Optimized Task Assignment and Predictive Maintenance for Industrial Machines using Markov Decision Process

arXiv.org Artificial Intelligence

The importance of predictive maintenance is well-recognized in the industrial sector for several reasons, e.g., it allows for the reduction in machine downtime, it helps in reducing the production cost, and it is useful in enhancing the life of machines. Consequently, predictive maintenance is one of the key areas of research among the scientific community. Initially, the predictive maintenance used to be time-based but later on (with the advances in sensing technology), condition-based maintenance (CBM) gained more popularity. Maintenance of machine tools involve two key stages, i.e., diagnosis and prognosis. Prognosis deals with the prediction of remaining useful life (RUL) of the machine whereas diagnosis is concerned with detection and identification of various faults in the machine. Major approaches for prognosis include data-based approaches, knowledge-based approaches, and physics (model) based approaches. Diagnosis on the other hand is based on centralized or distributed approaches [1]. Key challenges in predictive maintenance include 1) Dealing with the noisy sensor data, 2) Uncertainty in the operating conditions, and 3) Diversity of tasks assigned to the machine. A comparison between time-based and condition-based maintenance strategies has been presented in [2].


Anytime-Competitive Reinforcement Learning with Policy Prior

arXiv.org Artificial Intelligence

This paper studies the problem of Anytime-Competitive Markov Decision Process (A-CMDP). Existing works on Constrained Markov Decision Processes (CMDPs) aim to optimize the expected reward while constraining the expected cost over random dynamics, but the cost in a specific episode can still be unsatisfactorily high. In contrast, the goal of A-CMDP is to optimize the expected reward while guaranteeing a bounded cost in each round of any episode against a policy prior. We propose a new algorithm, called Anytime-Competitive Reinforcement Learning (ACRL), which provably guarantees the anytime cost constraints. The regret analysis shows the policy asymptotically matches the optimal reward achievable under the anytime competitive constraints. Experiments on the application of carbon-intelligent computing verify the reward performance and cost constraint guarantee of ACRL.


Regret Analysis of Policy Gradient Algorithm for Infinite Horizon Average Reward Markov Decision Processes

arXiv.org Artificial Intelligence

In this paper, we consider an infinite horizon average reward Markov Decision Process (MDP). Distinguishing itself from existing works within this context, our approach harnesses the power of the general policy gradient-based algorithm, liberating it from the constraints of assuming a linear MDP structure. We propose a policy gradient-based algorithm and show its global convergence property. We then prove that the proposed algorithm has $\tilde{\mathcal{O}}({T}^{3/4})$ regret. Remarkably, this paper marks a pioneering effort by presenting the first exploration into regret-bound computation for the general parameterized policy gradient algorithm in the context of average reward scenarios.


Distilling LLMs' Decomposition Abilities into Compact Language Models

arXiv.org Artificial Intelligence

Large Language Models (LLMs) have demonstrated proficiency in their reasoning abilities, yet their large size presents scalability challenges and limits any further customization. In contrast, compact models offer customized training but often fall short in solving complex reasoning tasks. This study focuses on distilling the LLMs' decomposition skills into compact models using offline reinforcement learning. We leverage the advancements in the LLM's capabilities to provide feedback and generate a specialized task-specific dataset for training compact models. These models not only excel at straightforward tasks such as summarization and sentiment analysis but, with adept prompting, demonstrate proficiency in handling reasoning tasks that demand mathematical and logical abilities (Huang & Chang, 2022). Notably, Chain-of-Thoughts (CoT) prompting (Wei et al., 2022) and its variations (Kojima et al., 2022; Wang et al., 2022) have proven to be promising and relatively simple techniques for enhancing LLMs' reasoning capabilities. Within the realm of complex reasoning, the ability to decompose intricate questions into a set of simpler sub-questions represents a crucial and understudied component (Shridhar et al., 2022). While existing works predominantly focus on end-to-end solutions for reasoning (Zhou et al., 2022; Lyu et al., 2023), the specific aspect of breaking down complex questions into simpler components has received limited attention. The creation of specialized datasets and benchmarks is integral to advancing the field of Deep Learning (Guss et al., 2019; Vinyals et al., 2019; Fu et al., 2020; Kurenkov et al., 2023). This work addresses the gap in understanding and exploration of the reasoning subquestioning process by providing a dataset and baselines for further research in this direction. Compounding the challenge is the computational overhead associated with large model sizes, making reasoning tasks computationally expensive and time-consuming when tuning models. Concurrently, approaches similar to Chain-of-Thoughts (CoT) may incur expenses, given that models with superior reasoning abilities are not available for free. In response, distilling distinct components of the reasoning process into smaller models emerges as a promising avenue for research.


Position Paper: Generalized grammar rules and structure-based generalization beyond classical equivariance for lexical tasks and transduction

arXiv.org Artificial Intelligence

Compositional generalization is one of the main properties which differentiates lexical learning in humans from state-of-art neural networks. We propose a general framework for building models that can generalize compositionally using the concept of Generalized Grammar Rules (GGRs), a class of symmetry-based compositional constraints for transduction tasks, which we view as a transduction analogue of equivariance constraints in physics-inspired tasks. Besides formalizing generalized notions of symmetry for language transduction, our framework is general enough to contain many existing works as special cases. We present ideas on how GGRs might be implemented, and in the process draw connections to reinforcement learning and other areas of research.


Approximate Control for Continuous-Time POMDPs

arXiv.org Artificial Intelligence

This stochastic filtering approach is especially appealing for the control of such partially observed dynamical systems. This includes among others, e.g., control problems This work proposes a decision-making framework with noisy sensor measurements, such as grasping for partially observable systems in continuous and navigation in robotics (Kurniawati et al., 2008) or time with discrete state and action cognitive medium access control (Zhao et al., 2005) for spaces. As optimal decision-making becomes communication systems. For finding decision strategies, intractable for large state spaces we employ which use the available observational data to control approximation methods for the filtering and the system at hand, a solid framework can be found the control problem that scale well with an increasing in the area of optimal control (Stengel, 1994).


Universal Imitation Games

arXiv.org Artificial Intelligence

Alan Turing proposed in 1950 a framework called an imitation game to decide if a machine could think. Using mathematics developed largely after Turing -- category theory -- we analyze a broader class of universal imitation games (UIGs), which includes static, dynamic, and evolutionary games. In static games, the participants are in a steady state. In dynamic UIGs, "learner" participants are trying to imitate "teacher" participants over the long run. In evolutionary UIGs, the participants are competing against each other in an evolutionary game, and participants can go extinct and be replaced by others with higher fitness. We use the framework of category theory -- in particular, two influential results by Yoneda -- to characterize each type of imitation game. Universal properties in categories are defined by initial and final objects. We characterize dynamic UIGs where participants are learning by inductive inference as initial algebras over well-founded sets, and contrast them with participants learning by conductive inference over the final coalgebra of non-well-founded sets. We briefly discuss the extension of our categorical framework for UIGs to imitation games on quantum computers.


Leveraging Approximate Model-based Shielding for Probabilistic Safety Guarantees in Continuous Environments

arXiv.org Artificial Intelligence

Shielding is a popular technique for achieving safe reinforcement learning (RL). However, classical shielding approaches come with quite restrictive assumptions making them difficult to deploy in complex environments, particularly those with continuous state or action spaces. In this paper we extend the more versatile approximate model-based shielding (AMBS) framework to the continuous setting. In particular we use Safety Gym as our test-bed, allowing for a more direct comparison of AMBS with popular constrained RL algorithms. We also provide strong probabilistic safety guarantees for the continuous setting. In addition, we propose two novel penalty techniques that directly modify the policy gradient, which empirically provide more stable convergence in our experiments.


MobilityDL: A Review of Deep Learning From Trajectory Data

arXiv.org Artificial Intelligence

Trajectory data combines the complexities of time series, spatial data, and (sometimes irrational) movement behavior. As data availability and computing power have increased, so has the popularity of deep learning from trajectory data. This review paper provides the first comprehensive overview of deep learning approaches for trajectory data. We have identified eight specific mobility use cases which we analyze with regards to the deep learning models and the training data used. Besides a comprehensive quantitative review of the literature since 2018, the main contribution of our work is the data-centric analysis of recent work in this field, placing it along the mobility data continuum which ranges from detailed dense trajectories of individual movers (quasi-continuous tracking data), to sparse trajectories (such as check-in data), and aggregated trajectories (crowd information).