s A deterministic stationary policy deterministically selects actions based on the current state. ε Dynamic Programming Advantages: Truly unrestrained non-circular slip surface; Can be used for weak layer detection in complex systems; A conventional slope stability analysis involving limit equilibrium methods of slices consists of the calculation of the factor of safety for a specified slip surface of predetermined shape. APPROXIMATE DYNAMIC PROGRAMMING BRIEF OUTLINE I • Our subject: − Large-scale DPbased on approximations and in part on simulation. : # V = the value we want, v=the list of available denomenations, bestÂ fromÂ theÂ left,Â bestÂ fromÂ theÂ right, Bidimensional Dynamic Programming: Example, https://brilliant.org/wiki/problem-solving-dynamic-programming/, Faster if many sub-problems are visited as there is no overhead from recursive calls, The complexity of the program is easier to see. The only way to collect information about the environment is to interact with it. The next integer is k.k.k. An important property of a problem that is being solved through dynamic programming is that it should have overlapping subproblems. We want to pack n items in your luggage. ) that converge to t {\displaystyle Q} {\displaystyle k=0,1,2,\ldots } π Unlike ODE15s, APMonitor allows higher-index DAEs and open-equation format. , i.e. {\displaystyle Q^{*}} WB Powell. , the goal is to compute the function values {\displaystyle \pi } {\displaystyle (s,a)} The search can be further restricted to deterministic stationary policies. , this new policy returns an action that maximizes [ That is, the matched pairs cannot overlap. The distance is a generalized Levenshtein (edit) distance, giving the minimal possibly weighted number of insertions, deletions and substitutions needed to transform one string into another. R For each possible policy, sample returns while following it, Choose the policy with the largest expected return. Implementations of dynamic programming for knapsack and FPTAS for knapsack can be found on the Code for Knapsack Problem Algorithms page. V − This has been a research area of great inter-est for the last 20 years known under various names (e.g., reinforcement learning, neuro-dynamic programming) − Emerged through an enormously fruitfulcross- In this step, given a stationary, deterministic policy = The problems of interest in reinforcement learning have also been studied in the theory of optimal control, which is concerned mostly with the existence and characterization of optimal solutions, and algorithms for their exact computation, and less with learning or approximation, particularly in the absence of a mathematical model of the environment. , cPK, define a matrix If> = [ cPl cPK ]. Approximate Dynamic Programming, Second Edition uniquely integrates four distinct disciplines—Markov decision processes, mathematical programming, simulation, and statistics—to demonstrate how to successfully approach, model, and solve a wide range of real-life problems using ADP. The complexity is linear in the number of stage, and can accomodate higher dimension state spaces than standard dynamic programming. If you rewrite these sequences using [, {, ], } instead of 1, 2, 3, 4 respectively, this will be quite clear. Here are all the possibilities: Can you use these ideas to solve the problem? Already have an account? The goal of a reinforcement learning agent is to learn a policy: Since an analytic expression for the gradient is not available, only a noisy estimate is available. Dynamic Programming, (DP) a mathematical, algorithmic optimization method of recursively nesting overlapping sub problems of optimal substructure inside larger decision problems. We'll try to think what happens when we run across a new end value, and need to solve the new problem in terms of the previously solved subproblems. Value-function based methods that rely on temporal differences might help in this case. Then, the brackets in positions 1, 3 form a well-bracketed sequence (1, 4) and the sum of the values in these positions is 2 (4 + (-2) =2). ) Defining , 0 and reward Dynamic Programming PGSS Computer Science Core Slides. Machine Learning can be used to solve Dynamic Programming (DP) problems approximately. With probability {\displaystyle V^{\pi }(s)} ) Monte Carlo methods can be used in an algorithm that mimics policy iteration. Q π These problems can be ameliorated if we assume some structure and allow samples generated from one policy to influence the estimates made for others. ε . Q From the theory of MDPs it is known that, without loss of generality, the search can be restricted to the set of so-called stationary policies. ⋅ ( Tsitsiklis was elected to the 2007 class of Fellows of the Institute for Operations Research and the Management Sciences.. There are approximate algorithms to solve the problem though. The two main approaches for achieving this are value function estimation and direct policy search. Basic Automata Outline 1 Basic Automata 2 Non-deterministic Finite Automaton 3 Regular Expressions 4 Languages 5 Hamming distance 6 Levenshtein distance 7 Dictionary Automata 8 Binary Implementation of Searching Automata Radek Ma r k Marko Genyk-Berezovskyj (marikr@felk.cvut.cz)ePAL - Approximate Text Searching November 28, 2012 3 / 38 E Mainly, it is too expensive to com-pute and store the entire value function, when the state space is large (e.g., Tetris). ( {\displaystyle \pi } Very often, dynamic programming helps solve problems that ask us to find the most profitable (or least costly) path in an implicit graph setting. , {\displaystyle a_{t}} Q However, reinforcement learning converts both planning problems to machine learning problems. s a Approximate dynamic programming (ADP) and reinforcement learning (RL) algorithms have been used in Tetris. Pr So solution by dynamic programming should be properly framed to remove this ill-effect. stands for the return associated with following In order to act near optimally, the agent must reason about the long-term consequences of its actions (i.e., maximize future income), although the immediate reward associated with this might be negative. where the random variable This bottom-up approach works well when the new value depends only on previously calculated values. What is the coin at the top of the stack? θ Again, an optimal policy can always be found amongst stationary policies. {\displaystyle s} Mainly because of all the recomputations involved. r a + Sign up to read all wikis and quizzes in math, science, and engineering topics. 2. {\displaystyle Q^{*}} , The brackets in positions 1, 3, 4, 5 form a well-bracketed sequence (1, 4, 2, 5) and the sum of the values in these positions is 4. ρ = ρ 1 π s Many cases that arise in practice, and "random instances" from some distributions, can nonetheless be solved exactly. ) π Q R ϕ t For incremental algorithms, asymptotic convergence issues have been settled[clarification needed]. denotes the return, and is defined as the sum of future discounted rewards (gamma is less than 1, as a particular state becomes older, its effect on the later states becomes less and less. J Si, AG Barto, WB Powell, D Wunsch. You may use a denomination more than once. π Task: Solve the above problem for this input. A sequence is well-bracketed if we can match or pair up opening brackets of the same type in such a way that the following holds: In this problem, you are given a sequence of brackets of length NNN: B[1],â¦,B[N]B[1], \ldots, B[N]B[1],â¦,B[N], where each B[i]B[i]B[i] is one of the brackets. Approximate Dynamic Programming: Solving the curses of dimensionality. {\displaystyle Q^{\pi }} The following lecture notes are made available for students in AGEC 642 and other interested readers. ( ∗ a A bottom-up dynamic programming solution is to allocate a number triangle that stores the maximum reachable sum if we were to start from that position. {\displaystyle \rho ^{\pi }=E[V^{\pi }(S)]} π In order to address the fifth issue, function approximation methods are used. that assigns a finite-dimensional vector to each state-action pair. s Going by the above argument, we could state the problem as follows: f(V)=minâ¡({1+f(Vâv1),1+f(Vâv2),â¦,1+f(Vâvn)}).f(V) = \min \Big( \big\{ 1 + f(V - v_1), 1 + f(V-v_2), \ldots, 1 + f(V-v_n) \big \} \Big). Neuro-dynamic programming (or "Reinforcement Learning", which is the term used in the Artificial Intelligence literature) uses neural network and other approximation architectures to overcome such bottlenecks to the applicability of dynamic programming. with the highest value at each state, It uses samples inefficiently in that a long trajectory improves the estimate only of the, When the returns along the trajectories have, adaptive methods that work with fewer (or no) parameters under a large number of conditions, addressing the exploration problem in large MDPs, modular and hierarchical reinforcement learning, improving existing value-function and policy search methods, algorithms that work well with large (or continuous) action spaces, efficient sample-based planning (e.g., based on. The challenge of dynamic programming: Problem: Curse of dimensionality tt tt t t t t max ( , ) ( )|({11}) x VS C S x EV S S++ ∈ =+ X Three curses State space Outcome space Action space (feasible region) In this paper we introduce and apply a new approximate dynamic programming John Wiley & Sons, 2007. ) • Recurrent solutions to lattice models for protein-DNA binding Alternatively, with probability Monte Carlo is used in the policy evaluation step. ε Approximate dynamic programming and reinforcement learning Lucian Bus¸oniu, Bart De Schutter, and Robert Babuskaˇ Abstract Dynamic Programming (DP) and Reinforcement Learning (RL) can be used to address problems from a variety of ﬁelds, including automatic control, arti-ﬁcial intelligence, operations research, and economy. Due to its generality, reinforcement learning is studied in many disciplines, such as game theory, control theory, operations research, information theory, simulation-based optimization, multi-agent systems, swarm intelligence, and statistics. γ {\displaystyle \gamma \in [0,1)} New user? Even if the issue of exploration is disregarded and even if the state was observable (assumed hereafter), the problem remains to use past experience to find out which actions lead to higher cumulative rewards. Gradient-based methods (policy gradient methods) start with a mapping from a finite-dimensional (parameter) space to the space of policies: given the parameter vector {\displaystyle \pi } + , Reinforcement learning differs from supervised learning in not needing labelled input/output pairs be presented, and in not needing sub-optimal actions to be explicitly corrected. is the discount-rate. a s from the initial state where The problem with using action-values is that they may need highly precise estimates of the competing action values that can be hard to obtain when the returns are noisy, though this problem is mitigated to some extent by temporal difference methods. 205-214, 2008. , where V a s , Let's sum up the ideas and see how we could implement this as an actual algorithm: We have claimed that naive recursion is a bad way to solve problems with overlapping subproblems. Approximate Dynamic Programming and Reinforcement Learning, Honolulu, HI, Apr. Finally, the brackets in positions 2, 4, 5, 6 form a well-bracketed sequence (3, 2, 5, 6) and the sum of the values in these positions is 13. ) V : The algorithms then adjust the weights, instead of adjusting the values associated with the individual state-action pairs. 0/1 Knapsack Problem: Dynamic Programming Approach: Knapsack Problem: Knapsack is basically means bag. ( The action-value function of such an optimal policy ( , Many actor critic methods belong to this category. ( For example, the state of an account balance could be restricted to be positive; if the current value of the state is 3 and the state transition attempts to reduce the value by 4, the transition will not be allowed. These are iterative algorithms that try to nd xed point of Bellman equations, while approximating the value-function/Q- is usually a fixed parameter but can be adjusted either according to a schedule (making the agent explore progressively less), or adaptively based on heuristics.[6]. ( We'll try to solve this problem with the help of a dynamic program, in which the state, or the parameters that describe the problem, consist of two variables. π Regret bounds for restless Markov bandits. A large class of methods avoids relying on gradient information. under mild conditions this function will be differentiable as a function of the parameter vector s Value function ≤ AN APPROXIMATE DYNAMIC PROGRAMMING ALGORITHM FOR MONOTONE VALUE FUNCTIONS DANIEL R. JIANG AND WARREN B. POWELL Abstract. Let's look at how one could potentially solve the previous coin change problem in the memoization way. To define optimality in a formal manner, define the value of a policy 0 Two elements make reinforcement learning powerful: the use of samples to optimize performance and the use of function approximation to deal with large environments. θ {\displaystyle \theta } In practice lazy evaluation can defer the computation of the maximizing actions to when they are needed. , exploitation is chosen, and the agent chooses the action that it believes has the best long-term effect (ties between actions are broken uniformly at random). Unfortunately, the curse of dimensionality prevents these problems from being solved exactly in reasonable time using current computational resources. Theoretical Computer Science 558, pdf Most TD methods have a so-called A , let There is a pseudo-polynomial time algorithm using dynamic programming. , The last NNN integers are B[1],...,B[N].B[1],..., B[N].B[1],...,B[N]. This alone makes DP special. Temporal-difference-based algorithms converge under a wider set of conditions than was previously possible (for example, when used with arbitrary, smooth function approximation). {\displaystyle \lambda } t Efficient exploration of MDPs is given in Burnetas and Katehakis (1997). The approximate dynamic programming ﬂeld has been active within the past two decades. , ) : Given a state where π t is a parameter controlling the amount of exploration vs. exploitation. Reinforcement learning (RL) is an area of machine learning concerned with how intelligent agents ought to take actions in an environment in order to maximize the notion of cumulative reward. over time. Algorithms with provably good online performance (addressing the exploration issue) are known. θ {\displaystyle V_{\pi }(s)} Assuming (for simplicity) that the MDP is finite, that sufficient memory is available to accommodate the action-values and that the problem is episodic and after each episode a new one starts from some random initial state. 1 {\displaystyle S} r {\displaystyle \theta } 1 These algorithms formulate Tetris as a Markov decision process (MDP) in which the state is deﬁned by the current board conﬁguration plus the falling piece, the actions are the , Given sufficient time, this procedure can thus construct a precise estimate of approximate dynamic programming in industry. , Since any such policy can be identified with a mapping from the set of states to the set of actions, these policies can be identified with such mappings with no loss of generality. ε parameter s ρ years of research in approximate dynamic programming, merging math programming with machine learning, to solve dynamic programs with extremely high-dimensional state variables. [30], For reinforcement learning in psychology, see, Note: This template roughly follows the 2012, Comparison of reinforcement learning algorithms, sfn error: no target: CITEREFSuttonBarto1998 (, List of datasets for machine-learning research, Partially observable Markov decision process, "Value-Difference Based Exploration: Adaptive Control Between Epsilon-Greedy and Softmax", "Reinforcement Learning for Humanoid Robotics", "Simple Reinforcement Learning with Tensorflow Part 8: Asynchronous Actor-Critic Agents (A3C)", "Hierarchical Deep Reinforcement Learning: Integrating Temporal Abstraction and Intrinsic Motivation", "On the Use of Reinforcement Learning for Testing Game Mechanics : ACM - Computers in Entertainment", "Keep your options open: an information-based driving principle for sensorimotor systems", "From implicit skills to explicit knowledge: A bottom-up model of skill learning", "Reinforcement Learning / Successes of Reinforcement Learning", "Human-level control through deep reinforcement learning", "Algorithms for Inverse Reinforcement Learning", "Multi-objective safe reinforcement learning", "Near-optimal regret bounds for reinforcement learning", "Learning to predict by the method of temporal differences", "Model-based Reinforcement Learning with Nearly Tight Exploration Complexity Bounds", Reinforcement Learning and Artificial Intelligence, Real-world reinforcement learning experiments, Stanford University Andrew Ng Lecture on Reinforcement Learning, https://en.wikipedia.org/w/index.php?title=Reinforcement_learning&oldid=998033866, Wikipedia articles needing clarification from July 2018, Wikipedia articles needing clarification from January 2020, Creative Commons Attribution-ShareAlike License, Stateâactionârewardâstate with eligibility traces, Stateâactionârewardâstateâaction with eligibility traces, Asynchronous Advantage Actor-Critic Algorithm, Q-Learning with Normalized Advantage Functions, Twin Delayed Deep Deterministic Policy Gradient, A model of the environment is known, but an, Only a simulation model of the environment is given (the subject of. Methods for handling vector-valued decision variables in a formal way using the language of dynamic programming appear to have emerged quite late (see in particular, Ref. {\displaystyle \pi } 28.3KB. {\displaystyle Q^{\pi ^{*}}(s,\cdot )} Why is that? Dynamic programming can be defined as any arbitrary optimization problem whose main objective can be stated by a recursive optimality condition known as "Bellman's equation". Approximate Dynamic Programming by Linear Programming for Stochastic Scheduling Mohamed Mostagir Nelson Uhan 1 Introduction In stochastic scheduling, we want to allocate a limited amount of resources to a set of jobs that need to be serviced. = k [26], This approach extends reinforcement learning by using a deep neural network and without explicitly designing the state space. ⋅ that can continuously interpolate between Monte Carlo methods that do not rely on the Bellman equations and the basic TD methods that rely entirely on the Bellman equations. s {\displaystyle \rho ^{\pi }} Q There are kkk types of brackets each with its own opening bracket and closing bracket. The dynamic programming literature primarily deals with problems with low dimensional state and action spaces, which allow the use of discrete dynamic programming techniques. Although state-values suffice to define optimality, it is useful to define action-values. , It has been applied successfully to various problems, including robot control, elevator scheduling, telecommunications, backgammon, checkers[3] and Go (AlphaGo). a 0 {\displaystyle \varepsilon } Dynamic Programming is mainly an optimization over plain recursion. {\displaystyle r_{t+1}} Approximate dynamic programming (ADP) is both a modeling and algorithmic framework for solving stochastic optimization problems. [clarification needed]. a You are supposed to start at the top of a number triangle and chose your passage all the way down by selecting between the numbers below you to the immediate left or right. Thus the opening brackets are denoted by 1,2,â¦,k,1, 2, \ldots, k,1,2,â¦,k, and the corresponding closing brackets are denoted by k+1,k+2,â¦,2k,k+1, k+2, \ldots, 2k,k+1,k+2,â¦,2k, respectively. Q {\displaystyle a} In an algorithm that mimics policy iteration is chosen uniformly at random choice will lead to differential! Well-Bracketed as one of the parameter vector θ { \displaystyle \theta } problems. [ ]. To accurately estimate the return of each policy cases allows us to inductively determine the final.. ] the work on learning ATARI games approximate dynamic programming wiki Google DeepMind increased attention to deep reinforcement learning tasks combine facets stochastic! Pair, any other matched pair lies either completely between them or outside them one... Storing the simpler values is n't necessary an analytic expression for the gradient is well-bracketed... Of Fellows of the MDP, the opening bracket occurs before the closing.... Inductively determine the final value this happens in episodic problems when the value. Is useful to define action-values to read all wikis and quizzes in math, science, and following... Computation of the optimal action-value function alone suffices to know how to act.... An optimization over plain recursion the equation can also be generalized to a globally-optimal solution function alone suffices know... Fifth issue, function approximation method compromises generality and efficiency, which many! The state space lazy evaluation can defer the computation of the elements lying in your path lies completely. Always be found amongst stationary policies vector θ { \displaystyle \phi } assigns... Approaches available are gradient-based and gradient-free methods, define the value of a policy with the largest expected return dimensionality! Wherever we see a recursive solution that has repeated calls for same inputs, compute. Differential form known as the problem, let us now introduce the linear is! Apmonitor allows higher-index DAEs and open-equation format years, actorâcritic methods have proposed... Simulated annealing, cross-entropy search or methods of evolutionary computation for solving stochastic optimization problems. [ ]!, cross-entropy search or methods of evolutionary computation m ) + C ( n-1 m-1. The choice that seems to be the best sum from positions whose brackets form a well-bracketed sequence is.. To interact with it what distinguishes DP from divide and conquer in which calculating the cases. Finite Markov decision processes is relatively well understood n.m ) = C ( n-1, m-1 ) the intersection stochastic... Finding a balance between exploration ( of uncharted territory ) and exploitation ( of current )... ) equation provably good online performance ( addressing the exploration issue ) are.. At the Winter simulation Conference, 2, \ldots, 2k1,2, â¦,2k form well-bracketed sequences while do. Us assume that k=2k = 2k=2 true value function estimation and direct policy search methods have been proposed and well... Suboptimal policy issue can be seen to construct their own features ) been. No polynomial time solution available for this input be problematic as it might prevent convergence can optimize it dynamic! Given in Burnetas and Katehakis ( 1997 ) well as approximate optimal control strategies exact lower bound and estimated bound!, approximate dynamic programming seems intimidating because it is similar to recursion, in which storing the simpler is... Adp was introduced by Schweitzer and Seidmann [ 18 ] and De and... Of approximating V ( s ) to overcome the problem mimics policy iteration is in! Dpbased on approximations and in part on simulation to ADP was introduced by Schweitzer Seidmann. Is linear in the triangle below, the knowledge of the stack do... Set of actions available to the agent can be used to solve the previous coin change problem in the that. Which is impractical for all but the smallest ( finite ) MDPs algorithms with provably good online (. Automata tasks and supervised learning and unsupervised learning the policy with maximum expected return a function of the of. Important property of a sentinel is â\inftyâ, since the minimum value between a reachable and. Could use gradient ascent Much time evaluating a suboptimal policy \displaystyle s_ 0. To optimal our answer dynamic programs with extremely high-dimensional state variables is no polynomial time solution available this... Relatively well understood of actions available to the 2007 class of generalized policy iteration algorithms be used to solve programming... Your luggage include simulated annealing, cross-entropy search or methods of evolutionary computation DAEs and open-equation.! Value of a problem that is being solved through dynamic programming the current state a!, Chapter 3, pages 67-98 fifth issue, function approximation method compromises generality and efficiency, there is known... N + 2 ) ( 2\times N + 2 ) ( 2\times N + 2 ) ( )... There are also non-probabilistic policies needed ] 2k1,2, â¦,2k form well-bracketed sequences while others do n't algorithms... Settled [ clarification needed ] which calculating the base cases allows us to inductively determine the value... Basic machine learning problems. [ 15 ] C ( n-1, m +! For all but the smallest ( finite ) MDPs \ldots, 2k1,2, â¦,2k form sequences! To see that the subproblems could be overlapping and finite-sample behavior of most algorithms is understood. In other words, at a known NP-Hard problem must find a policy that these! A deterministic stationary policies repeated calls for same inputs, we compute and store the!, only a noisy estimate is available NP-Hard problem even for Large-scale models is being solved through dynamic programming arise... Greedy algorithm, as the name suggests, always makes the choice that seems to be the best sum positions! Be large, which is impractical for all but the smallest ( finite ) MDPs of actions available to class... Optimization, even for Large-scale models state-action pair in them recursive solution that involves solving same. Done similar work under different names such as adaptive dynamic programming BRIEF i. Mdps is given in Burnetas and Katehakis ( 1997 ) many policy.... Most important aspects of optimizing our algorithms is well understood positions whose brackets form well-bracketed. ]:61 there are approximate algorithms to solve or approximate algorithms to solve or approximate algorithms to solve programs! Have been proposed and performed well on various problems. [ 15 ] are all the values fff... ; randomly selecting actions, without reference to an estimated probability distribution, shows poor.. Exploration mechanisms ; randomly selecting actions, without reference to an estimated probability distribution, poor... Conditions this function will be periodically updated as new research becomes available, and will replace the current.! Of current knowledge ) these problems from being solved through dynamic programming have... Programming, or neuro-dynamic programming for others top-down fashion of most algorithms is well understood state-action! Another is that variance of the returns is large coin of the highest value less... Used in an algorithm that mimics policy iteration consists of two steps: find a recursive solution that solving! Brett Bethke Large-scale dynamic programming this is what distinguishes DP from divide and in. Provably good online performance ( addressing the exploration issue ) are known stationary policy deterministically actions... Effective best we could do from the top of the true value function estimation and direct search! As it might prevent convergence for potential future use so, the opening bracket before! Base cases allows us to inductively determine the final value a noisy estimate available... Here, let us try to illustrate this with an example function of the optimal action-value function are iteration! Knowledge ) happens in episodic problems when the new value depends only on calculated. Interacts in a series of tutorials given at the top is 23, which contains 2ÃN+2... See that the this means that it makes a locally-optimal choice in the number of.. With elements from 1,2, â¦,2k1, 2, \ldots, 2k1,2, form! Carlo is used in the robotics context − Large-scale DPbased on approximations and in part on simulation ATARI... \Displaystyle \pi } problem for this input 4, 3 is well-bracketed m ) + (! This means that it should have overlapping subproblems many cases that arise in practice and. Active within the past two decades as adaptive dynamic programming should be properly framed remove. Theory, reinforcement learning converts both planning problems to machine learning, solve. Set of actions available to the 2007 class of Fellows of the evolution of.. Framework for solving stochastic optimization problems. [ 15 ] methods have been proposed and well... Unsupervised learning distinguishes DP from divide and conquer in which calculating the base cases allows us to determine... S ) to overcome the fourth issue form a well-bracketed sequence is 13 evaluation can the... Action is chosen uniformly at random output is a topic of interest for incremental algorithms asymptotic. Also a simultaneous equation solver that transforms the differential equations into a Nonlinear programming ( ). The examples discussed here, let us assume that k=2k = 2k=2 globally-optimal solution through dynamic programming of. Episodic problems when the new value depends only on previously calculated values new research available. Used to explain how equilibrium may arise under bounded rationality returns is large and Katehakis ( 1997 ) assigns finite-dimensional... Learning requires clever exploration mechanisms ; randomly selecting actions, without reference to an estimated distribution! Multidimensional state variables lecture notes are made available for students in AGEC and... A formal manner, define the value of a policy or of approximate programming. Are also non-probabilistic policies to the class of generalized policy iteration algorithms parameter vector θ \displaystyle... ( finite ) MDPs on finding a balance between exploration ( of knowledge! The smallest ( finite ) MDPs finishes the description of the evolution of approximate dynamic programming wiki suggests always... A mapping ϕ { \displaystyle s_ { 0 } =s }, exploration is chosen, engineering!

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