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Jinkyoo Park

52 accepted papers

2026

Active Attacks: Red-teaming LLMs via Adaptive Environments

ICML 2026poster

We address the challenge of automatically generating diverse attack prompts for large language models (LLMs) that elicit harmful behaviors (e.g., insults, sexual content) and are used for safety fine-tuning. While several prior approaches train LLMs with reinforcement learning (RL) to generate such …

Cited by 0SourceScholar
2026

Diffusion Alignment as Variataional Expectation-Maximization

ICLR 2026poster

Diffusion alignment aims to optimize diffusion models for the downstream objective. While existing methods based on reinforcement learning or direct backpropagation achieve considerable success in maximizing rewards, they often suffer from reward over-optimization and mode collapse. We introduce Dif…

Cited by 0SourcecodeScholar
2026

Diffusion Fine-Tuning via Reparameterized Policy Gradient of the Soft Q-Function

ICLR 2026poster

Diffusion models excel at generating high-likelihood samples but often require alignment with downstream objectives. Existing fine-tuning methods for diffusion models significantly suffer from reward over-optimization, resulting in high-reward but unnatural samples and degraded diversity. To mitigat…

Cited by 0SourceScholar
2026

Reinforced Sequential Monte Carlo for Amortised Sampling

ICML 2026spotlight

This paper proposes a synergy of amortised and particle-based methods for sampling from distributions defined by unnormalised density functions. We state a connection between sequential Monte Carlo (SMC) and neural sequential samplers trained by maximum-entropy reinforcement learning (MaxEnt RL), wh…

Cited by 0SourceScholar
2026

RouteFinder: Towards Foundation Models for Vehicle Routing Problems

ICML 2026poster

This paper introduces RouteFinder, a comprehensive foundation model framework to tackle different Vehicle Routing Problem (VRP) variants. Our core idea is that a foundation model for VRPs should be able to represent variants by treating each as a subset of a generalized problem equipped with differe…

Cited by 0SourcecodeScholar
2026

Towards Real-World Routing with Neural Combinatorial Optimization

ICLR 2026poster

The practical deployment of Neural Combinatorial Optimization (NCO) for Vehicle Routing Problems (VRPs) is hindered by a critical sim-to-real gap. This gap stems not only from training on oversimplified Euclidean data but also from node-based architectures incapable of handling the node-and-edge-bas…

Cited by 0SourcecodeScholar
2026

TrajEvo: Trajectory Prediction Heuristics Design via LLM-driven Evolution

AAAI 2026technical

Trajectory prediction is a crucial task in modeling human behavior, especially in safety-critical fields such as social robotics and autonomous vehicle navigation. Traditional heuristics based on handcrafted rules often lack accuracy, while recently proposed deep learning approaches suffer from comp

Cited by 0SourcePDFScholar
2026

USPR: Learning a Unified Solver for Profiled Routing

AAAI 2026technical

The Profiled Vehicle Routing Problem (PVRP) extends the classical VRP by incorporating vehicle–client-specific preferences and constraints, reflecting real‑world requirements such as zone restrictions and service‑level preferences. While recent reinforcement‑learning solvers have shown promising per

Cited by 0SourcePDFScholar
2025

Adaptive teachers for amortized samplers

ICLR 2025poster

Amortized inference is the task of training a parametric model, such as a neural network, to approximate a distribution with a given unnormalized density where exact sampling is intractable. When sampling is modeled as a sequential decision-making process, reinforcement learning (RL) methods, such a…

2025

Ant Colony Sampling with GFlowNets for Combinatorial Optimization

AISTATS 2025poster

We present the Generative Flow Ant Colony Sampler (GFACS), a novel meta-heuristic method that hierarchically combines amortized inference and parallel stochastic search. Our method first leverages Generative Flow Networks (GFlowNets) to amortize a multi-modal prior distribution over combinatorial so…

Cited by 0SourceScholar
2025

Generative Flows on Synthetic Pathway for Drug Design

ICLR 2025poster

Generative models in drug discovery have recently gained attention as efficient alternatives to brute-force virtual screening. However, most existing models do not account for synthesizability, limiting their practical use in real-world scenarios. In this paper, we propose RxnFlow, which sequentiall…

2025

Human Implicit Preference-Based Policy Fine-tuning for Multi-Agent Reinforcement Learning in USV Swarm

IROS 2025

Multi-Agent Reinforcement Learning (MARL) has shown promise in solving complex problems involving cooperation and competition among agents, such as an Unmanned Surface Vehicle (USV) swarm used in search and rescue, surveillance, and vessel protection. However, aligning system behavior with user pref

Cited by 5SourceScholar
2025

Improved Off-policy Reinforcement Learning in Biological Sequence Design

ICML 2025poster

Designing biological sequences with desired properties is challenging due to vast search spaces and limited evaluation budgets. Although reinforcement learning methods use proxy models for rapid reward evaluation, insufficient training data can cause proxy misspecification on out-of-distribution inp…

2025

Learning Strategy Representation for Imitation Learning in Multi-Agent Games

AAAI 2025technical

The offline datasets for imitation learning (IL) in multi-agent games typically contain player trajectories exhibiting diverse strategies, which necessitate measures to prevent learning algorithms from acquiring undesirable behaviors. Learning representations for these trajectories is an effective a…

Cited by 0SourcePDFScholar
2025

Learning to Sample Effective and Diverse Prompts for Text-to-Image Generation

CVPR 2025poster

Recent advances in text-to-image diffusion models have demonstrated impressive image generation capabilities. However, it remains challenging to control the generation process with desired properties (e.g., aesthetic quality, user intention), which can be expressed as black-box reward functions. Rec…

2025

MOFFlow: Flow Matching for Structure Prediction of Metal-Organic Frameworks

ICLR 2025poster

Metal-organic frameworks (MOFs) are a class of crystalline materials with promising applications in many areas such as carbon capture and drug delivery. In this work, we introduce MOFFlow, the first deep generative model tailored for MOF structure prediction. Existing approaches, including ab initio…

2025

PARCO: Parallel AutoRegressive Models for Multi-Agent Combinatorial Optimization

NeurIPS 2025poster

Combinatorial optimization problems involving multiple agents are notoriously challenging due to their NP-hard nature and the necessity for effective agent coordination. Despite advancements in learning-based methods, existing approaches often face critical limitations, including suboptimal agent co…

Cited by 0SourcecodeScholar
2025

Posterior Inference with Diffusion Models for High-dimensional Black-box Optimization

ICML 2025poster

Optimizing high-dimensional and complex black-box functions is crucial in numerous scientific applications. While Bayesian optimization (BO) is a powerful method for sample-efficient optimization, it struggles with the curse of dimensionality and scaling to thousands of evaluations. Recently, lever…

2024

Distributed Online Planning for Min-Max Problems in Networked Markov Games

RA-L 2024

Min-max problems are important in multi-agent sequential decision-making because they improve the performance of the worst-performing agent in the network. However, solving the multi-agent min-max problem is challenging. We propose a modular, distributed, online planning-based algorithm that is able

Cited by 1SourcecodeScholar
2024

Equity-Transformer: Solving NP-Hard Min-Max Routing Problems as Sequential Generation with Equity Context

AAAI 2024technical

Min-max routing problems aim to minimize the maximum tour length among multiple agents as they collaboratively visit all cities, i.e., the completion time. These problems include impactful real-world applications but are known as NP-hard. Existing methods are facing challenges, particularly in large…

2024

GTA: Generative Trajectory Augmentation with Guidance for Offline Reinforcement Learning

NeurIPS 2024poster

Offline Reinforcement Learning (Offline RL) presents challenges of learning effective decision-making policies from static datasets without any online interactions. Data augmentation techniques, such as noise injection and data synthesizing, aim to improve Q-function approximation by smoothing the l…

2024

Genetic-guided GFlowNets for Sample Efficient Molecular Optimization

NeurIPS 2024poster

The challenge of discovering new molecules with desired properties is crucial in domains like drug discovery and material design. Recent advances in deep learning-based generative methods have shown promise but face the issue of sample efficiency due to the computational expense of evaluating the re…

2024

Guided Trajectory Generation with Diffusion Models for Offline Model-based Optimization

NeurIPS 2024poster

Optimizing complex and high-dimensional black-box functions is ubiquitous in science and engineering fields. Unfortunately, the online evaluation of these functions is restricted due to time and safety constraints in most cases. In offline model-based optimization (MBO), we aim to find a design that…

2024

Learning to Scale Logits for Temperature-Conditional GFlowNets

ICML 2024poster

GFlowNets are probabilistic models that sequentially generate compositional structures through a stochastic policy. Among GFlowNets, temperature-conditional GFlowNets can introduce temperature-based controllability for exploration and exploitation. We propose *Logit-scaling GFlowNets* (Logit-GFN), a…

2024

Local Search GFlowNets

ICLR 2024spotlight

Generative Flow Networks (GFlowNets) are amortized sampling methods that learn a distribution over discrete objects proportional to their rewards. GFlowNets exhibit a remarkable ability to generate diverse samples, yet occasionally struggle to consistently produce samples with high rewards due to ov…

2024

Pessimistic Backward Policy for GFlowNets

NeurIPS 2024poster

This paper studies Generative Flow Networks (GFlowNets), which learn to sample objects proportionally to a given reward function through the trajectory of state transitions. In this work, we observe that GFlowNets tend to under-exploit the high-reward objects due to training on insufficient number o…

2024

ReEvo: Large Language Models as Hyper-Heuristics with Reflective Evolution

NeurIPS 2024poster

The omnipresence of NP-hard combinatorial optimization problems (COPs) compels domain experts to engage in trial-and-error heuristic design. The long-standing endeavor of design automation has gained new momentum with the rise of large language models (LLMs). This paper introduces Language Hyper-Heu…

2024

Symmetric Replay Training: Enhancing Sample Efficiency in Deep Reinforcement Learning for Combinatorial Optimization

ICML 2024poster

Deep reinforcement learning (DRL) has significantly advanced the field of combinatorial optimization (CO). However, its practicality is hindered by the necessity for a large number of reward evaluations, especially in scenarios involving computationally intensive function assessments. To enhance the…

2023

Bootstrapped Training of Score-Conditioned Generator for Offline Design of Biological Sequences

NeurIPS 2023poster

We study the problem of optimizing biological sequences, e.g., proteins, DNA, and RNA, to maximize a black-box score function that is only evaluated in an offline dataset. We propose a novel solution, bootstrapped training of score-conditioned generator (BootGen) algorithm. Our algorithm repeats a t…

2023

DevFormer: A Symmetric Transformer for Context-Aware Device Placement

ICML 2023poster

In this paper, we present DevFormer, a novel transformer-based architecture for addressing the complex and computationally demanding problem of hardware design optimization. Despite the demonstrated efficacy of transformers in domains including natural language processing and computer vision, their…

Cited by 21SourcePDFScholar
2023

Learning Efficient Surrogate Dynamic Models with Graph Spline Networks

NeurIPS 2023poster

While complex simulations of physical systems have been widely used in engineering and scientific computing, lowering their often prohibitive computational requirements has only recently been tackled by deep learning approaches. In this paper, we present GraphSplineNets, a novel deep-learning method…

Cited by 3SourcePDFScholar
2023

Meta-SAGE: Scale Meta-Learning Scheduled Adaptation with Guided Exploration for Mitigating Scale Shift on Combinatorial Optimization

ICML 2023poster

This paper proposes Meta-SAGE, a novel approach for improving the scalability of deep reinforcement learning models for combinatorial optimization (CO) tasks. Our method adapts pre-trained models to larger-scale problems in test time by suggesting two components: a scale meta-learner (SML) and sched…

2022

Efficient Approximate Inference for Stationary Kernel on Frequency Domain

ICML 2022spotlight

Based on the Fourier duality between a stationary kernel and its spectral density, modeling the spectral density using a Gaussian mixture density enables one to construct a flexible kernel, known as a Spectral Mixture kernel, that can model any stationary kernel. However, despite its expressive powe…

2022

Learning NP-Hard Multi-Agent Assignment Planning using GNN: Inference on a Random Graph and Provable Auction-Fitted Q-learning

NeurIPS 2022accept

This paper explores the possibility of near-optimally solving multi-agent, multi-task NP-hard planning problems with time-dependent rewards using a learning-based algorithm. In particular, we consider a class of robot/machine scheduling problems called the multi-robot reward collection problem (MRRC…

Cited by 2SourcePDFScholar
2022

Neural Solvers for Fast and Accurate Numerical Optimal Control

ICLR 2022poster

Synthesizing optimal controllers for dynamical systems often involves solving optimization problems with hard real-time constraints. These constraints determine the class of numerical methods that can be applied: computationally expensive but accurate numerical routines are replaced by fast and inac…

2022

Sym-NCO: Leveraging Symmetricity for Neural Combinatorial Optimization

NeurIPS 2022accept

Deep reinforcement learning (DRL)-based combinatorial optimization (CO) methods (i.e., DRL-NCO) have shown significant merit over the conventional CO solvers as DRL-NCO is capable of learning CO solvers less relying on problem-specific expert domain knowledge (heuristic method) and supervised labele…

2022

Transform Once: Efficient Operator Learning in Frequency Domain

NeurIPS 2022accept

Spectral analysis provides one of the most effective paradigms for information-preserving dimensionality reduction, as simple descriptions of naturally occurring signals are often obtained via few terms of periodic basis functions. In this work, we study deep neural networks designed to harness the…

2021

Differentiable Multiple Shooting Layers

NeurIPS 2021poster

We detail a novel class of implicit neural models. Leveraging time-parallel methods for differential equations, Multiple Shooting Layers (MSLs) seek solutions of initial value problems via parallelizable root-finding algorithms. MSLs broadly serve as drop-in replacements for neural ordinary differe…

Cited by 23SourcePDFScholar
2021

Learning Collaborative Policies to Solve NP-hard Routing Problems

NeurIPS 2021poster

Recently, deep reinforcement learning (DRL) frameworks have shown potential for solving NP-hard routing problems such as the traveling salesman problem (TSP) without problem-specific expert knowledge. Although DRL can be used to solve complex problems, DRL frameworks still struggle to compete with s…

2021

Neural Hybrid Automata: Learning Dynamics With Multiple Modes and Stochastic Transitions

NeurIPS 2021poster

Effective control and prediction of dynamical systems require appropriate handling of continuous-time and discrete, event-triggered processes. Stochastic hybrid systems (SHSs), common across engineering domains, provide a formalism for dynamical systems subject to discrete, possibly stochastic, stat…

Cited by 13SourcePDFScholar
2020

Hypersolvers: Toward Fast Continuous-Depth Models

NeurIPS 2020poster

The infinite-depth paradigm pioneered by Neural ODEs has launched a renaissance in the search for novel dynamical system-inspired deep learning primitives; however, their utilization in problems of non-trivial size has often proved impossible due to poor computational scalability. This work paves th…

2020

WATTNet: Learning to Trade FX via Hierarchical Spatio-Temporal Representation of Highly Multivariate Time Series

IJCAI 2020poster

Finance is a particularly challenging application area for deep learning models due to low noise-to-signal ratio, non-stationarity, and partial observability. Non-deliverable-forwards (NDF), a derivatives contract used in foreign exchange (FX) trading, presents additional difficulty in the form of l…

Cited by 0SourcePDFScholar