Modern Deep Reinforcement Learning Algorithms
Pith reviewed 2026-05-25 17:33 UTC · model grok-4.3
The pith
Combining classical reinforcement learning theory with deep neural networks produces algorithms that solve complex decision tasks.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Recent advances in Reinforcement Learning, grounded on combining classical theoretical results with Deep Learning paradigm, led to breakthroughs in many artificial intelligence tasks and gave birth to Deep Reinforcement Learning (DRL) as a field of research. The work reviews the latest DRL algorithms with emphasis on their theoretical basis, practical constraints, and empirical behaviors.
What carries the argument
The integration of classical RL theory with deep neural networks as the mechanism for scaling to complex problems.
Load-bearing premise
The algorithms selected for review are the most representative and important ones in the field at the time of writing.
What would settle it
Discovery of a major DRL algorithm from the review period that was omitted or whose reported theoretical and empirical properties were misstated.
Figures
read the original abstract
Recent advances in Reinforcement Learning, grounded on combining classical theoretical results with Deep Learning paradigm, led to breakthroughs in many artificial intelligence tasks and gave birth to Deep Reinforcement Learning (DRL) as a field of research. In this work latest DRL algorithms are reviewed with a focus on their theoretical justification, practical limitations and observed empirical properties.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper claims that recent advances in Reinforcement Learning, grounded on combining classical theoretical results with the Deep Learning paradigm, have led to breakthroughs in many AI tasks and the emergence of Deep Reinforcement Learning (DRL) as a field. It reviews the latest DRL algorithms with a focus on their theoretical justification, practical limitations, and observed empirical properties.
Significance. If the selected algorithms are representative and the summaries of theory, limitations, and empirics are accurate, the survey could provide a useful synthesis for researchers navigating DRL, particularly by connecting classical RL foundations to modern deep methods. The descriptive framing (no new derivations or predictions) makes the contribution dependent on coverage and fidelity rather than novelty of results.
major comments (1)
- [Abstract] Abstract: the claim to review 'latest DRL algorithms' is load-bearing for the paper's utility as a field map, yet no explicit selection criteria or justification for the chosen set of algorithms is provided; this risks omitting representative methods or over-weighting others, directly affecting the central descriptive claim.
minor comments (2)
- Ensure that empirical properties discussed for each algorithm are tied to specific cited experiments or benchmarks rather than general statements.
- Clarify the publication cutoff date for 'latest' algorithms to allow readers to assess timeliness of the review.
Simulated Author's Rebuttal
We thank the referee for the thoughtful review and the recommendation for minor revision. The single major comment identifies a genuine gap in the manuscript's framing as a survey, and we address it directly below.
read point-by-point responses
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Referee: [Abstract] Abstract: the claim to review 'latest DRL algorithms' is load-bearing for the paper's utility as a field map, yet no explicit selection criteria or justification for the chosen set of algorithms is provided; this risks omitting representative methods or over-weighting others, directly affecting the central descriptive claim.
Authors: We agree that the absence of explicit selection criteria weakens the paper's utility as a field map. In the revised version we will add a short subsection (likely in the introduction) that states the criteria: (i) recency, with emphasis on algorithms published or popularized after the 2013-2015 deep-RL breakthroughs; (ii) demonstrated impact, measured by subsequent citations and influence on follow-up work; and (iii) coverage of distinct algorithmic families (value-based, policy-gradient, actor-critic, model-based). We will also note that the survey is necessarily non-exhaustive and flag a few prominent omissions (e.g., certain offline RL or meta-RL methods) with brief justification. This addition directly responds to the referee's concern without altering the descriptive nature of the contribution. revision: yes
Circularity Check
Survey paper with no derivations or self-referential predictions
full rationale
This is a literature review surveying recent DRL algorithms and their properties. No original derivations, equations, fitted parameters, or predictive claims are made that could reduce to the paper's own inputs by construction. The central claim is a descriptive review of selected algorithms with attention to theory, limitations, and empirics; this holds independently of any self-citation and does not invoke uniqueness theorems, ansatzes, or renamings of results. No load-bearing steps match any of the enumerated circularity patterns.
Axiom & Free-Parameter Ledger
Reference graph
Works this paper leans on
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[1]
SELECTaRANDOMLYWITHPROBABILITY ε(t),ELSEa =argmax a ∑ iziζ∗ i (s,a,θ )
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[5]
FOREACHTRANSITIONTFROMTHEBATCHCOMPUTETARGET: P(y(T ) =r′ +γzi) =ζ∗ i ( s′,argmax a′ ∑ i ziζ∗ i (s′,a′,θ−),θ− )
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[7]
COMPUTELOSS: Loss = 1 B ∑ T KL(y(T ) ∥Z∗(s,a,θ ))
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[9]
IFt mod K = 0:θ− ←θ 4.3. 1uANTILE2EGRESSIOND1.(12-D1.) CATEGORICALD1.DISCOVEREDAGAPBETWEENTHEORYANDPRACTICEAS KL-DIVERGENCE,USEDINPRAC- TICALALGORITHM,ISTHEORETICALLYUNJUSTI 1ED.4HEOREM12HINTSTHATTHETRUEDIVERGENCEWESHOULDCARE ABOUTISACTUALLY7ASSERSTEINMETRIC,BUTITREMAINEDUNCLEARHOWITCOULDBEOPTIMIZEDUSINGONLY SAMPLESFROMTRANSITIONPROBABILITIES T. IN;3]ITWA...
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[10]
SELECTaRANDOMLYWITHPROBABILITY ε(t),ELSEa =argmax a 1 A ∑ iζ∗ i (s,a,θ )
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[12]
ADDOBSERVEDTRANSITIONTOEXPERIENCEREPLAY
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[13]
SAMPLEBATCHOFSIZEBFROMEXPERIENCEREPLAY
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[14]
FOREACHTRANSITIONTFROMTHEBATCHCOMPUTETHESUPPORTOFTARGETDISTRIBUTION: y(T )j =r′ +γζ∗ j ( s′,argmax a′ 1 A ∑ i ζ∗ i (s′,a′,θ−),θ− ) 26
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[15]
COMPUTELOSS: Loss = 1 BA ∑ T ∑ i ∑ j ( τi − I[ζ∗ i (s,a,θ )<y (T )j] ) ( ζ∗ i (s,a,θ ) −y(T )j )
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[17]
IFt mod K = 0:θ− ←θ 4.4. 2AINBOWD1. 3UCCESSOFDEEP1-LEARNINGENCOURAGEDAFULL-SCALERESEARCHOFVALUE-BASEDDEEPREINFORCEMENT LEARNINGBYSTUDYINGVARIOUSDRAWBACKSOFD1.ANDDEVELOPINGAUXILIARYEXTENSIONS. INMANYARTI- CLESSOMEEXTENSIONSFROMPREVIOUSRESEARCHWEREALREADYCONSIDEREDANDEMBEDDEDINCOMPARED ALGORITHMSDURINGEMPIRICALSTUDIES. IN2AINBOWD1.;7],SEVEN1-LEARNING-BASEDI...
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[18]
SELECTa =argmax a ∑ iziζ∗ i (s,a,θ,ε ),ε ∼ N (0,I )
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[19]
OBSERVETRANSITION(s,a,r′,s′, done)
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[20]
CONSTRUCTN-STEPTRANSITIONT = ( s,a, ∑N n=0γnr(n+1),s (N), done ) ANDADDITTO EXPERIENCEREPLAYWITHPRIORITY maxTρ(T )
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[21]
SAMPLEBATCHOFSIZEBFROMEXPERIENCEREPLAYUSINGPROBABILITIES P(T ) ∝ρ(T )α
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[22]
COMPUTEWEIGHTSFORTHEBATCH(WHEREMISTHESIZEOFEXPERIENCEREPLAYMEMORY) w(T ) = ( 1 M P(T ) )β(t)
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[23]
FOREACHTRANSITIONT = (s,a, ¯r, ¯s, done)FROMTHEBATCHCOMPUTETARGET(DETACHED FROMCOMPUTATIONALGRAPHTOPREVENTBACKPROPAGATION): ε1,ε 2 ∼ N (0,I ) P(y(T ) = ¯r +γNzi) =ζ∗ i ( ¯s,argmax ¯a ∑ i ziζ∗ i (¯s, ¯a,θ,ε 1),θ−,ε 2 )
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[24]
PROJECTy(T )ONSUPPORT {z0,z 1...z A−1}
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[25]
UPDATETRANSITIONPRIORITIES ρ(T ) ← KL(y(T ) ∥Z∗(s,a,θ,ε )),ε ∼ N (0,I )
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[26]
COMPUTELOSS: Loss = 1 B ∑ T w(T )ρ(T )
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[27]
MAKEASTEPOFGRADIENTDESCENTUSING ∂ Loss ∂θ
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[28]
IFt mod K = 0:θ− ←θ 28
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[29]
0OLICyGRADIENTALGORITHMS 5.1. 0OLICyGRADIENTTHEOREM ALTERNATIVEAPPROACHTOSOLVING2,TASKISDIRECTOPTIMIZATIONOFOBJECTIVE J(θ) = ET∼πθ ∑ t=1 γt−1rt → max θ (33) ASAFUNCTIONOF θ.0OLICYGRADIENTMETHODSPROVIDEAFRAMEWORKHOWTOCONSTRUCTANE ZCIENTOPTI- MIZATIONPROCEDUREBASEDONSTOCHASTIC 1RST-ORDEROPTIMIZATIONWITHIN2,SETTING. 7EWILLASSUMETHAT πθ(a | s)ISASTOCHASTICPOL...
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[30]
OBTAINAROLL-OUTOFSIZEBUSINGPOLICY π(θ)
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[31]
FOREACHTRANSITIONTFROMTHEROLL-OUTCOMPUTEADVANTAGEESTIMATION: Aπ(T ) =r′ +γV π φ (s′) −Vπ φ
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[32]
COMPUTETARGET(DETACHEDFROMCOMPUTATIONALGRAPHTOPREVENTBACKPROPAGATION): y(T ) =r′ +γV π φ (s′)
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COMPUTECRITICLOSS: Loss = 1 B ∑ T ( y(T ) −Vπ φ )2
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COMPUTECRITICGRADIENTS: ∇critic = ∂ Loss ∂φ
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COMPUTEACTORGRADIENT: ∇actor = 1 B ∑ T ∇θ logπθ(a |s)Aπ(T )
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MAKEASTEPOFGRADIENTDESCENTUSING ∇actor +α∇critic 5.4. GENERALIzEDADVANTAGEESTIMATION(GAE) 4HEREISADESIGNDILEMMAINADVANTAGEACTORCRITICALGORITHMCONCERNINGTHECHOICEWHETHERTO USETHECRITICTOESTIMATE Qπ(s,a )ANDINTRODUCEBIASINTOGRADIENTESTIMATIONORTORESTRICTCRITICEM- PLOYMENTONLYFORBASELINEANDCAUSEHIGHERVARIANCEWITHNECESSITYOFPLAYINGTHEWHOLEEPISODES FOREACHUPDA...
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OBTAINAROLL-OUTOFSIZERUSINGPOLICY π(θ),STORINGACTIONPROBABILITIESAS πold(a |s)
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[38]
FOREACHTRANSITIONT FROMTHEROLL-OUTCOMPUTEADVANTAGEESTIMATION(DETACHEDFROM COMPUTATIONALGRAPHTOPREVENTBACKPROPAGATION): Aπ(T ) =r′ +γV π φ (s′) −Vπ φ
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PERFORMn?epochsPASSESTHROUGHROLL-OUTUSINGBATCHESOFSIZE B;FOREACHBATCH: • COMPUTECRITICTARGET(DETACHEDFROMCOMPUTATIONALGRAPHTOPREVENTBACKPROPA- GATION): y(T ) =r′ +γV π φ (s′) • COMPUTECRITICLOSS: Loss = 1 B ∑ T ( y(T ) −Vπ φ )2 • COMPUTECRITICGRADIENTS: ∇critic = ∂ Loss ∂φ • COMPUTEIMPORTANCESAMPLINGWEIGHTS: rθ(T ) = πθ(a |s) πold(a |s) • COMPUTECLIPPEDIM...
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[40]
ExPERIMENTS 6.1. 3ETuP 7EPERFORMEDOUREXPERIMENTSUSINGCUSTOMIMPLEMENTATIONOFDISCUSSEDALGORITHMSATTEMPT- INGTOINCORPORATEBESTFEATURESFROMDI ffERENTOZCIALANDUNO ZCIALSOURCESANDUNIFYINGALLALGO- RITHMSINASINGLELIBRARYINTERFACE.4HEFULLCODEISAVAILABLEATOURGITHUB. 7HILECUSTOMIMPLEMENTATIONMIGHTNOTBETHEMOSTE ZCIENT,ITHINTEDUSSEVERALAMBIGUITIESIN ALGORITHMSWHICHARER...
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DISCuSSION 7EHAVECONCERNEDTWOMAINDIRECTIONSOFUNIVERSALMODEL-FREE2,ALGORITHMDESIGNANDAT- TEMPTEDTORECREATESEVERALSTATE-OF-ARTPIPELINES. 7HILETHEEXTENSIONSOFD1.AREREASONABLESOLUTIONSOFEVIDENTD1.PROBLEMS, THEIRE ffECT ISNOTCLEARLYSEENONSIMPLETASKSLIKE0ONG 36. CURRENTSTATE-OF-ARTINSINGLE-THREADEDVALUE-BASED APPROACH,2AINBOWD1.,ISFULLOFjGLUEANDTAPEzDECISIONSTHA...
work page internal anchor Pith review Pith/arXiv arXiv 2017
discussion (0)
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