Search Results for author: Heinz Koeppl

Found 63 papers, 17 papers with code

Augmenting Continuous Time Bayesian Networks with Clocks

no code implementations ICML 2020 Nicolai Engelmann, Dominik Linzner, Heinz Koeppl

Structured stochastic processes evolving in continuous time present a widely adopted framework to model phenomena occurring in nature and engineering.

Bounded Rationality Equilibrium Learning in Mean Field Games

no code implementations11 Nov 2024 Yannick Eich, Christian Fabian, Kai Cui, Heinz Koeppl

The resulting novel receding horizon (RH) MFGs are combined with QRE and existing approaches to model different aspects of bounded rationality in MFGs.

$\textit{GeoHard}$: Towards Measuring Class-wise Hardness through Modelling Class Semantics

no code implementations17 Jul 2024 Fengyu Cai, Xinran Zhao, Hongming Zhang, Iryna Gurevych, Heinz Koeppl

Recent advances in measuring hardness-wise properties of data guide language models in sample selection within low-resource scenarios.

Natural Language Understanding

$\texttt{MixGR}$: Enhancing Retriever Generalization for Scientific Domain through Complementary Granularity

1 code implementation15 Jul 2024 Fengyu Cai, Xinran Zhao, Tong Chen, Sihao Chen, Hongming Zhang, Iryna Gurevych, Heinz Koeppl

Recent studies show the growing significance of document retrieval in the generation of LLMs, i. e., RAG, within the scientific domain by bridging their knowledge gap.

Question Answering RAG +1

FPGA-Based Neural Thrust Controller for UAVs

no code implementations27 Mar 2024 Sharif Azem, David Scheunert, Mengguang Li, Jonas Gehrunger, Kai Cui, Christian Hochberger, Heinz Koeppl

The advent of unmanned aerial vehicles (UAVs) has improved a variety of fields by providing a versatile, cost-effective and accessible platform for implementing state-of-the-art algorithms.

Reinforcement Learning (RL)

Scaling up Dynamic Edge Partition Models via Stochastic Gradient MCMC

no code implementations29 Feb 2024 Sikun Yang, Heinz Koeppl

For large network data, we propose a stochastic gradient Markov chain Monte Carlo (SG-MCMC) algorithm for scalable inference in the proposed model.

Link Prediction

Negative-Binomial Randomized Gamma Markov Processes for Heterogeneous Overdispersed Count Time Series

no code implementations29 Feb 2024 Rui Huang, Sikun Yang, Heinz Koeppl

Modeling count-valued time series has been receiving increasing attention since count time series naturally arise in physical and social domains.

Imputation Time Series

A Poisson-Gamma Dynamic Factor Model with Time-Varying Transition Dynamics

no code implementations26 Feb 2024 Jiahao Wang, Sikun Yang, Heinz Koeppl, Xiuzhen Cheng, Pengfei Hu, Guoming Zhang

Probabilistic approaches for handling count-valued time sequences have attracted amounts of research attentions because their ability to infer explainable latent structures and to estimate uncertainties, and thus are especially suitable for dealing with \emph{noisy} and \emph{incomplete} count data.

Data Augmentation Time Series

Graph Structure Inference with BAM: Introducing the Bilinear Attention Mechanism

no code implementations12 Feb 2024 Philipp Froehlich, Heinz Koeppl

In statistics and machine learning, detecting dependencies in datasets is a central challenge.

Graph structure learning

Approximate Control for Continuous-Time POMDPs

1 code implementation2 Feb 2024 Yannick Eich, Bastian Alt, Heinz Koeppl

This work proposes a decision-making framework for partially observable systems in continuous time with discrete state and action spaces.

Decision Making

Learning Mean Field Games on Sparse Graphs: A Hybrid Graphex Approach

no code implementations23 Jan 2024 Christian Fabian, Kai Cui, Heinz Koeppl

This hybrid graphex learning approach leverages that the system mainly consists of a highly connected core and a sparse periphery.

Multi-agent Reinforcement Learning

Collaborative Optimization of the Age of Information under Partial Observability

no code implementations20 Dec 2023 Anam Tahir, Kai Cui, Bastian Alt, Amr Rizk, Heinz Koeppl

In this work, we devise a decentralized AoI-minimizing transmission policy for a number of sensor agents sharing capacity-limited, non-FIFO duplex channels that introduce random delays in communication with a common receiver.

Sparse Mean Field Load Balancing in Large Localized Queueing Systems

no code implementations20 Dec 2023 Anam Tahir, Kai Cui, Heinz Koeppl

Empirically, the proposed methodology performs well on several realistic and scalable wireless network topologies as compared to a number of well-known load balancing heuristics and existing scalable multi-agent reinforcement learning methods.

Multi-agent Reinforcement Learning reinforcement-learning +1

Learning Discrete-Time Major-Minor Mean Field Games

1 code implementation17 Dec 2023 Kai Cui, Gökçe Dayanıklı, Mathieu Laurière, Matthieu Geist, Olivier Pietquin, Heinz Koeppl

We propose a novel discrete time version of major-minor MFGs (M3FGs), along with a learning algorithm based on fictitious play and partitioning the probability simplex.

Learning to Cooperate and Communicate Over Imperfect Channels

no code implementations24 Nov 2023 Jannis Weil, Gizem Ekinci, Heinz Koeppl, Tobias Meuser

In addition to this message size selection, agents learn to encode and decode messages to improve their jointly trained policies.

Q-Learning

A Survey of Confidence Estimation and Calibration in Large Language Models

no code implementations14 Nov 2023 Jiahui Geng, Fengyu Cai, Yuxia Wang, Heinz Koeppl, Preslav Nakov, Iryna Gurevych

Assessing their confidence and calibrating them across different tasks can help mitigate risks and enable LLMs to produce better generations.

Language Modelling

Entropic Matching for Expectation Propagation of Markov Jump Processes

no code implementations27 Sep 2023 Bastian Alt, Heinz Koeppl

This paper addresses the problem of statistical inference for latent continuous-time stochastic processes, which is often intractable, particularly for discrete state space processes described by Markov jump processes.

Bayesian Inference

The TYC Dataset for Understanding Instance-Level Semantics and Motions of Cells in Microstructures

2 code implementations23 Aug 2023 Christoph Reich, Tim Prangemeier, Heinz Koeppl

In this paper, we introduce the trapped yeast cell (TYC) dataset, a novel dataset for understanding instance-level semantics and motions of cells in microstructures.

Learning Decentralized Partially Observable Mean Field Control for Artificial Collective Behavior

no code implementations12 Jul 2023 Kai Cui, Sascha Hauck, Christian Fabian, Heinz Koeppl

However, multi-agent RL (MARL) remains a challenge in terms of decentralization, partial observability and scalability to many agents.

Policy Gradient Methods Reinforcement Learning (RL)

An Instance Segmentation Dataset of Yeast Cells in Microstructures

1 code implementation15 Apr 2023 Christoph Reich, Tim Prangemeier, André O. Françani, Heinz Koeppl

The aim of the dataset and evaluation strategy is to facilitate the development of new cell segmentation approaches.

Cell Segmentation Image Segmentation +3

Bayesian Inference for Jump-Diffusion Approximations of Biochemical Reaction Networks

no code implementations13 Apr 2023 Derya Altıntan, Bastian Alt, Heinz Koeppl

The presented blocked Gibbs particle smoothing algorithm utilizes a sequential Monte Carlo method to estimate the latent states and performs distinct Gibbs steps for the parameters of a biochemical reaction network, by exploiting a jump-diffusion approximation model.

Bayesian Inference

Histopathological Image Classification based on Self-Supervised Vision Transformer and Weak Labels

1 code implementation17 Oct 2022 Ahmet Gokberk Gul, Oezdemir Cetin, Christoph Reich, Tim Prangemeier, Nadine Flinner, Heinz Koeppl

Here, we propose Self-ViT-MIL, a novel approach for classifying and localizing cancerous areas based on slide-level annotations, eliminating the need for pixel-wise annotated training data.

Histopathological Image Classification Image Classification +1

Forward-Backward Latent State Inference for Hidden Continuous-Time semi-Markov Chains

no code implementations17 Oct 2022 Nicolai Engelmann, Heinz Koeppl

We show that non-sampling-based latent state inference used in HSMM's can be generalized to latent Continuous-Time semi-Markov Chains (CTSMC's).

Reinforcement Learning with Non-Exponential Discounting

no code implementations27 Sep 2022 Matthias Schultheis, Constantin A. Rothkopf, Heinz Koeppl

In contrast, in economics and psychology, it has been shown that humans often adopt a hyperbolic discounting scheme, which is optimal when a specific task termination time distribution is assumed.

Decision Making Model-based Reinforcement Learning +4

Scalable Task-Driven Robotic Swarm Control via Collision Avoidance and Learning Mean-Field Control

no code implementations15 Sep 2022 Kai Cui, Mengguang Li, Christian Fabian, Heinz Koeppl

Thus, we combine collision avoidance and learning of mean-field control into a unified framework for tractably designing intelligent robotic swarm behavior.

Collision Avoidance Multi-agent Reinforcement Learning +3

Mean Field Games on Weighted and Directed Graphs via Colored Digraphons

no code implementations8 Sep 2022 Christian Fabian, Kai Cui, Heinz Koeppl

Graphon mean field games (GMFGs) on the other hand provide a scalable and mathematically well-founded approach to learning problems that involve a large number of connected agents.

Multi-agent Reinforcement Learning

Learning Sparse Graphon Mean Field Games

1 code implementation8 Sep 2022 Christian Fabian, Kai Cui, Heinz Koeppl

Although the field of multi-agent reinforcement learning (MARL) has made considerable progress in the last years, solving systems with a large number of agents remains a hard challenge.

Multi-agent Reinforcement Learning

A Survey on Large-Population Systems and Scalable Multi-Agent Reinforcement Learning

no code implementations8 Sep 2022 Kai Cui, Anam Tahir, Gizem Ekinci, Ahmed Elshamanhory, Yannick Eich, Mengguang Li, Heinz Koeppl

The analysis and control of large-population systems is of great interest to diverse areas of research and engineering, ranging from epidemiology over robotic swarms to economics and finance.

Decision Making Epidemiology +6

Decentralized Coordination in Partially Observable Queueing Networks

no code implementations29 Aug 2022 Jiekai Jia, Anam Tahir, Heinz Koeppl

We consider communication in a fully cooperative multi-agent system, where the agents have partial observation of the environment and must act jointly to maximize the overall reward.

Learning Mean-Field Control for Delayed Information Load Balancing in Large Queuing Systems

1 code implementation9 Aug 2022 Anam Tahir, Kai Cui, Heinz Koeppl

In this work, we consider a multi-agent load balancing system, with delayed information, consisting of many clients (load balancers) and many parallel queues.

Hypergraphon Mean Field Games

no code implementations30 Mar 2022 Kai Cui, Wasiur R. KhudaBukhsh, Heinz Koeppl

We propose an approach to modelling large-scale multi-agent dynamical systems allowing interactions among more than just pairs of agents using the theory of mean field games and the notion of hypergraphons, which are obtained as limits of large hypergraphs.

Learning Graphon Mean Field Games and Approximate Nash Equilibria

1 code implementation ICLR 2022 Kai Cui, Heinz Koeppl

Recent advances at the intersection of dense large graph limits and mean field games have begun to enable the scalable analysis of a broad class of dynamical sequential games with large numbers of agents.

OSS-Net: Memory Efficient High Resolution Semantic Segmentation of 3D Medical Data

1 code implementation20 Oct 2021 Christoph Reich, Tim Prangemeier, Özdemir Cetin, Heinz Koeppl

Occupancy networks (O-Nets) are an alternative for which the data is represented continuously in a function space and 3D shapes are learned as a continuous decision boundary.

3D Semantic Segmentation Liver Segmentation +2

Variational Inference for Continuous-Time Switching Dynamical Systems

no code implementations NeurIPS 2021 Lukas Köhs, Bastian Alt, Heinz Koeppl

Since many areas, such as biology or discrete-event systems, are naturally described in continuous time, we present a model based on an Markov jump process modulating a subordinated diffusion process.

Time Series Time Series Analysis +1

Load Balancing in Compute Clusters with Delayed Feedback

1 code implementation17 Sep 2021 Anam Tahir, Bastian Alt, Amr Rizk, Heinz Koeppl

In this paper, we provide a partially observable (PO) model that captures the load balancing decisions in parallel buffered systems under limited information of delayed acknowledgements.

Decision Making

Multi-StyleGAN: Towards Image-Based Simulation of Time-Lapse Live-Cell Microscopy

1 code implementation15 Jun 2021 Christoph Reich, Tim Prangemeier, Christian Wildner, Heinz Koeppl

Time-lapse fluorescent microscopy (TLFM) combined with predictive mathematical modelling is a powerful tool to study the inherently dynamic processes of life on the single-cell level.

Descriptive Generative Adversarial Network +2

Active Learning of Continuous-time Bayesian Networks through Interventions

no code implementations31 May 2021 Dominik Linzner, Heinz Koeppl

We propose a novel criterion for experimental design based on a variational approximation of the expected information gain.

Active Learning Experimental Design

Discrete-Time Mean Field Control with Environment States

no code implementations30 Apr 2021 Kai Cui, Anam Tahir, Mark Sinzger, Heinz Koeppl

Multi-agent reinforcement learning methods have shown remarkable potential in solving complex multi-agent problems but mostly lack theoretical guarantees.

Deep Reinforcement Learning Multi-agent Reinforcement Learning +3

Moment-Based Variational Inference for Stochastic Differential Equations

no code implementations1 Mar 2021 Christian Wildner, Heinz Koeppl

We construct the variational process as a controlled version of the prior process and approximate the posterior by a set of moment functions.

Variational Inference

Approximately Solving Mean Field Games via Entropy-Regularized Deep Reinforcement Learning

no code implementations2 Feb 2021 Kai Cui, Heinz Koeppl

We show that all discrete-time finite MFGs with non-constant fixed point operators fail to be contractive as typically assumed in existing MFG literature, barring convergence via fixed point iteration.

Deep Reinforcement Learning reinforcement-learning +1

Maximizing Information Gain for the Characterization of Biomolecular Circuits

no code implementations8 Jan 2021 Tim Prangemeier, Christian Wildner, Maleen Hanst, Heinz Koeppl

Quantitatively predictive models of biomolecular circuits are important tools for the design of synthetic biology and molecular communication circuits.

Experimental Design Informativeness

Poisson channel with binary Markov input and average sojourn time constraint

no code implementations5 Jan 2021 Mark Sinzger, Maximilian Gehri, Heinz Koeppl

Determining its capacity is an optimization problem with respect to two parameters: the average sojourn times of the promoter's active (ON) and inactive (OFF) state.

Attention-Based Transformers for Instance Segmentation of Cells in Microstructures

1 code implementation19 Nov 2020 Tim Prangemeier, Christoph Reich, Heinz Koeppl

For the specific use case, the proposed method surpasses the state-of-the-art tools for semantic segmentation and additionally predicts the individual object instances.

Cell Detection Cell Segmentation +4

POMDPs in Continuous Time and Discrete Spaces

no code implementations NeurIPS 2020 Bastian Alt, Matthias Schultheis, Heinz Koeppl

We consider the problem of optimal decision making in such discrete state and action space systems under partial observability.

Decision Making Deep Reinforcement Learning

Continuous-Time Bayesian Networks with Clocks

no code implementations1 Jul 2020 Nicolai Engelmann, Dominik Linzner, Heinz Koeppl

Structured stochastic processes evolving in continuous time present a widely adopted framework to model phenomena occurring in nature and engineering.

A Variational Perturbative Approach to Planning in Graph-based Markov Decision Processes

no code implementations4 Dec 2019 Dominik Linzner, Heinz Koeppl

We present a novel approximate solution method for multi-agent Markov decision problems on graphs, based on variational perturbation theory.

Correlation Priors for Reinforcement Learning

no code implementations NeurIPS 2019 Bastian Alt, Adrian Šošić, Heinz Koeppl

Many decision-making problems naturally exhibit pronounced structures inherited from the characteristics of the underlying environment.

Imitation Learning reinforcement-learning +2

Scalable Structure Learning of Continuous-Time Bayesian Networks from Incomplete Data

no code implementations NeurIPS 2019 Dominik Linzner, Michael Schmidt, Heinz Koeppl

Instead of sampling and scoring all possible structures individually, we assume the generator of the CTBN to be composed as a mixture of generators stemming from different structures.

Time Series Time Series Analysis

Moment-Based Variational Inference for Markov Jump Processes

no code implementations14 May 2019 Christian Wildner, Heinz Koeppl

We propose moment-based variational inference as a flexible framework for approximate smoothing of latent Markov jump processes.

Variational Inference

Cluster Variational Approximations for Structure Learning of Continuous-Time Bayesian Networks from Incomplete Data

no code implementations NeurIPS 2018 Dominik Linzner, Heinz Koeppl

Existing approximation techniques, such as sampling and low-order variational methods, either scale unfavorably in system size, or are unsatisfactory in terms of accuracy.

Time Series Time Series Analysis

Collapsed Variational Inference for Nonparametric Bayesian Group Factor Analysis

1 code implementation10 Sep 2018 Sikun Yang, Heinz Koeppl

Group factor analysis (GFA) methods have been widely used to infer the common structure and the group-specific signals from multiple related datasets in various fields including systems biology and neuroimaging.

Variational Inference

Dependent Relational Gamma Process Models for Longitudinal Networks

no code implementations ICML 2018 Sikun Yang, Heinz Koeppl

Within the latent space, our framework models the birth and death dynamics of individual groups via a thinning function.

Data Augmentation

A Poisson Gamma Probabilistic Model for Latent Node-group Memberships in Dynamic Networks

no code implementations28 May 2018 Sikun Yang, Heinz Koeppl

We present a probabilistic model for learning from dynamic relational data, wherein the observed interactions among networked nodes are modeled via the Bernoulli Poisson link function, and the underlying network structure are characterized by nonnegative latent node-group memberships, which are assumed to be gamma distributed.

Social and Information Networks

Inverse Reinforcement Learning via Nonparametric Spatio-Temporal Subgoal Modeling

no code implementations1 Mar 2018 Adrian Šošić, Elmar Rueckert, Jan Peters, Abdelhak M. Zoubir, Heinz Koeppl

Advances in the field of inverse reinforcement learning (IRL) have led to sophisticated inference frameworks that relax the original modeling assumption of observing an agent behavior that reflects only a single intention.

Active Learning reinforcement-learning +2

A Bayesian Approach to Policy Recognition and State Representation Learning

no code implementations4 May 2016 Adrian Šošić, Abdelhak M. Zoubir, Heinz Koeppl

Learning from demonstration (LfD) is the process of building behavioral models of a task from demonstrations provided by an expert.

Representation Learning

Inverse Reinforcement Learning in Swarm Systems

no code implementations17 Feb 2016 Adrian Šošić, Wasiur R. KhudaBukhsh, Abdelhak M. Zoubir, Heinz Koeppl

Inverse reinforcement learning (IRL) has become a useful tool for learning behavioral models from demonstration data.

reinforcement-learning Reinforcement Learning +1

A variational approach to path estimation and parameter inference of hidden diffusion processes

no code implementations3 Aug 2015 Tobias Sutter, Arnab Ganguly, Heinz Koeppl

We consider a hidden Markov model, where the signal process, given by a diffusion, is only indirectly observed through some noisy measurements.

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