Heydar Soudani

Heydar Soudani

PhD Candidate
Radboud University
Nijmegen, The Netherlands
Applied Researcher · LLM Agents · Post-Training & RL · Retrieval · Uncertainty Quantification
PhD expected 2027 · Open to full-time roles

I am a final-year PhD candidate in Computer Science at Radboud University, where I train, build, and evaluate LLM systems with two focuses: LLM agents (deep research agents, agentic search, tool use) and uncertainty quantification. My goal is to build reliable AI systems that solve complex information-seeking and reasoning tasks.

Alongside my research, I work with industry on applied LLM problems. Most recently, at Thomson Reuters Labs, I built a multi-agent search system for legal research and a controller for deep research agents based on trajectory-level signals, improving both the search trajectory and final task performance (EMNLP 2026). Before that, at KPN, I brought uncertainty estimation to a customer-facing RAG chatbot.

I work hands-on with LLM fine-tuning (full, LoRA), RL post-training (RLVR), retrieval and reranking, synthetic data generation, and benchmark construction. My work has been published at ACL, EMNLP, COLING, SIGIR, SIGIR-AP, ICTIR, and ACM Computing Surveys.

Education
Feb 2023 — Present (expected 2027)

Ph.D. Computer Science

Radboud University, Netherlands

Trustworthy Generative Information Access

Supervisors: Faegheh Hasibi, Arjen de Vries

Sep 2019 — Jun 2022

M.Sc. Computer Engineering

Sharif University of Technology, Iran

Predicting Novelty Concepts in Data Stream

Supervisor: Hamid Beigy

Sep 2014 — Sep 2019

B.Sc. Electrical Engineering

Polytechnic of Tehran, Iran

Providing new cloud services on the Kubernetes platform

Supervisor: Hassan Taheri

Sep 2016 — Sep 2018

B.Sc. Computer Engineering

Polytechnic of Tehran, Iran

Minor degree, taken alongside the Electrical Engineering major.

Work Experience
Feb 2023 — Present

PhD Candidate

Radboud University · Nijmegen, Netherlands

Trustworthy Generative Information Access. Uncertainty quantification for RAG and search agents, benchmarks for deep research agents, and fine-tuning vs. RAG for long-tail knowledge.

Published at SIGIR, ACL, ICTIR, SIGIR-AP, and ACM Computing Surveys.

Supervisors: Faegheh Hasibi, Arjen de Vries

Uncertainty QuantificationDeep Research AgentsRAGLLM Post-trainingBenchmarking
Nov 2025 — May 2026

Data Scientist Intern (Applied AI Research)

Thomson Reuters Labs · Zug, Switzerland · Remote

Built a modular agentic search system for legal research, and RAAC, a controller that cut deep research agents' search calls by 14 on average with up to 10% higher accuracy (EMNLP 2026).

Supervisors: Navid Rekabsaz, Elizabeth Lingg

Agentic SearchLegal DomainAWS SageMaker / BedrockvLLMLangfuse
May 2025 — Oct 2025

Data Scientist Intern

KPN · Amsterdam, Netherlands · On-site

Brought uncertainty estimation to KPN's customer-facing RAG chatbot to flag unreliable answers.

Supervisor: Gianluigi Bardelloni

Uncertainty QuantificationRAGKnowledge Graphs
Dec 2017 — Jun 2022 · 4 yrs 7 mos

Web Developer

Andishe Fartak Amirkabir (Atrovan) · Part-time · Tehran, Iran

Built 4 production web products (smart metering, fleet management, home automation, building management) in a 10+ person Scrum team.

React.jsJavaScriptREST APIsPostgreSQLDockerKubernetes
Jan 2016 — Oct 2017

Research Assistant

Control of Multi Vehicle Systems Lab (CMVL) · Polytechnic of Tehran

Collaborated on AVR and Raspberry Pi programming, computer vision for localization, and PCB design with Altium Designer.

Supervisor: Farzaneh Abdollahi

Computer VisionEmbedded SystemsRobotics
Technical Skills

⬡ LLM Training & Post-training

SFT Full Fine-tuning LoRA / QLoRA RL Post-training (GRPO, PPO, DPO, RLVR) Reward Design Synthetic Data Generation vLLM LiteLLM OpenRouter

⬡ Agents & RAG

Prompt Engineering LangChain / LangGraph Query Decomposition & Reformulation Sparse Retrieval (BM25, SPLADE) Dense Retrieval (E5, Qwen3-Embedding) LLM Rerankers Rank Fusion FAISS

⬡ Uncertainty & Evaluation

Uncertainty Quantification Calibration LLM-as-Judge Benchmark Construction Trajectory Analysis

⬡ ML / DL

PyTorch TensorFlow HF Transformers PEFT HF Datasets scikit-learn NumPy pandas

⬡ Languages

Python SQL Bash JavaScript C / C++

⬡ MLOps & Cloud

AWS (SageMaker, Bedrock) HPC / Slurm Langfuse Weights & Biases Docker Kubernetes

⬡ Software Engineering

Git Linux REST APIs PostgreSQL System Design Claude Code Cursor
Publications
2026

When Deep Research Agents Stagnate: Enhancing Reasoning with Retrieval-Aware Agent Control

Heydar Soudani, Elizabeth Lingg, Faegheh Hasibi, Navid Rekabsaz
Conference on Empirical Methods in Natural Language Processing (EMNLP)
2026

Uncertainty Quantification for Retrieval-Augmented Reasoning

Heydar Soudani, Hamed Zamani, Faegheh Hasibi
The 49th International ACM SIGIR Conference on Research and Development in Information Retrieval
2026

Total Recall QA: A Verifiable Evaluation Suite for Deep Research Agents

Mahta Rafiee, Heydar Soudani, Zahra Abbasiantaeb, Mohammad Aliannejadi, Faegheh Hasibi, Hamed Zamani
The 49th International ACM SIGIR Conference on Research and Development in Information Retrieval
2026

Uncertainty Quantification for Multimodal Retrieval Augmented Generation

Simon Binz, Heydar Soudani, Faegheh Hasibi
The 2026 International ACM SIGIR Conference on Innovative Concepts and Theories in Information Retrieval (ICTIR)
2026

A Survey on Recent Advances in Conversational Data Generation

Heydar Soudani, Roxana Petcu, Evangelos Kanoulas, Faegheh Hasibi
ACM Computing Surveys
2025

Why Uncertainty Estimation Methods Fall Short in RAG: An Axiomatic Analysis

Heydar Soudani, Evangelos Kanoulas, Faegheh Hasibi
Findings of the Association for Computational Linguistics (ACL)
2024

Fine Tuning vs. Retrieval Augmented Generation for Less Popular Knowledge

Heydar Soudani, Evangelos Kanoulas, Faegheh Hasibi
The 2024 Annual International ACM SIGIR Conference on Research and Development in Information Retrieval in the Asia Pacific Region (SIGIR-AP)
2022

Persian Natural Language Inference: A Meta-learning Approach

Heydar Soudani, Mohammad Hassan Mojab, Hamid Beigy
International Conference on Computational Linguistics (COLING)
Paper Slides Code Poster
Academic Service
Reviewing
Full papers
  • ACL 2025
  • EMNLP 2026
  • SIGIR 2026
  • CIKM 2026
  • WWW 2027
Short papers
  • ACL 2024
  • SIGIR 2026
  • ECIR 2026
  • WSDM 2026
  • ECIR 2027
Journals
  • TOIS
  • ACM Computing Surveys
  • Knowledge-Based Systems
Thesis Supervision
  • Uncertainty Quantification for Multimodal Retrieval-Augmented Generation
  • Failure Modes of Deep Research Agents in Context-Aided Forecasting