Philipp Christmann
Contact
Philipp Christmann
Max-Planck-Institut für InformatikDepartment 5: Databases and Information Systems
Question Answering
| Office: |
Campus E1 4,
Room 422 Saarland Informatics Campus 66123 Saarbrücken Germany |
|---|---|
| Email: |
Get my email address via email |
| Links: |
Personal Homepage Google Scholar DBLP GitHub |
About
Philipp Christmann was a PhD student at the Max Planck Institute for Informatics, supervised by Rishiraj Saha Roy and Gerhard Weikum.
He defended his PhD thesis titled "Question Answering over Heterogeneous Sources" in February 2026 with summa cum laude.
Philipp is now a postdoctoral researcher at the CISPA Helmholtz Center for Information Security, advised by Mario Fritz. Link to his personal website: https://philippchristmann.com.
Philipp is now a postdoctoral researcher at the CISPA Helmholtz Center for Information Security, advised by Mario Fritz. Link to his personal website: https://philippchristmann.com.
Research Interests
- Question Answering
- Knowledge Graphs
- Dialogue Systems
Publications
- P. Christmann and G. Weikum,
Recursive Question Understanding for Complex Question Answering over Heterogeneous Personal Data,
ACL '25 (Findings Long Paper).
[Preprint] [Demo] [Website] [Code] [Video]
- P. Christmann and G. Weikum,
RAG-based Question Answering over Heterogeneous Data and Text,
IEEE Data Engineering Bulletin '24 (Special Issue on Retrieval-Augmented Generation).
[Preprint] [Website] [Code]
- P. Christmann, S. Vakulenko, I. T. Sorodoc, B. Byrne, and A. de Gispert,
Retrieving Contextual Information for Long-Form Question Answering using Weak Supervision,
EMNLP '24 (Findings Short Paper).
[Preprint]
- Zhen Jia, P. Christmann, and G. Weikum,
Faithful Temporal Question Answering over Heterogeneous Sources,
WWW '24 (Research Track Long Paper).
[Preprint] [Website] [Code] [Poster]
- Zhen Jia, P. Christmann, and G. Weikum,
TIQ: A Benchmark for Temporal Question Answering with Implicit Time Constraints,
TempWeb@WWW '24.
[Website] [Code] [Slides]
- P. Christmann, R. Saha Roy, and G. Weikum,
CompMix: A Benchmark for Heterogeneous Question Answering,
WWW '24 (Resource Track Paper).
[Preprint] [Website] [Slides] [Video]
- P. Christmann, R. Saha Roy, and G. Weikum,
Explainable Conversational Question Answering Heterogeneous Sources via Iterative Graph Neural Networks,
SIGIR '23 (Research Track Long Paper).
[Preprint] [Website] [Code] [Demo] [Slides] [Video] [User study]
- P. Christmann, R. Saha Roy, and G. Weikum,
CLOCQ: A Toolkit for Fast and Easy Access to Knowledge Bases,
BTW '23 (Short Paper).
[Code] [API] [Poster] [Slides]
- P. Christmann, R. Saha Roy, and G. Weikum,
Question Entity and Relation Linking to Knowledge Bases via CLOCQ,
SMART@ISWC '22.
[Code] [API] [Slides] [Video]
- P. Christmann, R. Saha Roy, and G. Weikum,
Conversational Question Answering on Heterogeneous Sources,
SIGIR '22 (Research Track Long Paper).
[Preprint] [Website] [Code] [Demo] [Slides] [Video]
- P. Christmann,
Explainable Conversational Question Answering over Heterogeneous Sources,
SIGIR '22 (Doctoral Consortium Paper).
- P. Christmann, R. Saha Roy, and G. Weikum,
Beyond NED: Fast and Effective Search Space Reduction for Complex Question Answering over Knowledge Bases,
WSDM '22 (Research Track Long Paper).
[Preprint] [API] [Website] [Code] [Poster] [Slides] [Video] [Extended Video]
Recognitions
- Received a SIGIR student travel grant for SIGIR 2022.
- Outstanding PC Member Award for WSDM 2022.
- Received a SIGIR registration grant for WSDM 2022.
- Received a SIGIR student travel grant for CIKM 2019.
Professional Activities
- Invited talk at Search-oriented Conversational AI (SCAI) on "Conversational Question Answering on Heterogeneous Sources", Madrid, 15 July 2022.
- Invited talk at Amazon Alexa AI on "Conversational Question Answering on Heterogeneous Sources", remote, 13 June 2022.
- Reviewer for TOIS (2022, 2023).
- Program committee member at
- WSDM 2026 (research track long paper)
- WSDM 2026 (resource track)
- ECIR 2026 (long paper track)
- CIKM 2025 (resource track)
- SIGIR 2025 (long & short paper tracks)
- ECIR 2025 (long & short paper tracks)
- CIKM 2024 (short paper track)
- SIGIR 2024 (long & short paper tracks)
- CIKM 2023 (applied research track)
- SIGIR 2023 (short paper track)
- SIGKDD 2023 (applied science track)
- CCKS 2022 (applied science track)
- CIKM 2022 (short paper track)
- SIGKDD 2022 (applied science track)
- WSDM 2022 (research track long paper) - featuring among 21 outstanding PC members
- CIKM 2021 (short paper track)
- CIKM 2020 (short paper track)
Education
- April 2021 - present:
PhD student in Computer Science at the Saarland Informatics Campus, Saarbrücken and the Max-Planck-Institut für Informatik (supervisors: Prof. Gerhard Weikum and Dr. Rishiraj Saha Roy).
- August 2019 - March 2021:
Master in Computer Science, Saarland Informatics Campus, Saarbrücken
Title of Master's Thesis: CLOCQ: Efficient Search Space Reduction for Complex Question Answering over Knowledge Bases (supervisors: Prof. Gerhard Weikum and Dr. Rishiraj Saha Roy).
→ Revised version published at WSDM '22 (Research Track Long Paper)
- October 2015 - July 2019:
Bachelor in Computer Science, Saarland Informatics Campus, Saarbrücken
Title of Bachelor's Thesis: A Method and Benchmark for Conversational Question Answering over Knowledge Graphs (supervisors: Prof. Gerhard Weikum and Dr. Rishiraj Saha Roy).
→ Revised version published at CIKM '19 (Research Track Long Paper)
- June 2015:
Abitur at the Christian von Mannlich Gymnasium, Homburg.
Recent Positions
- September 2023 - January 2024:
Applied Science Internship, Amazon Alexa AI, Barcelona, Spain
Research project on retrieval-augmented generation with large language models (mentor: Svitlana Vakulenko, manager: Adrià de Gispert).
- March 2022 - present:
Sys-Admin, Max-Planck-Institut für Informatik, Saarland Informatics Campus, Germany
Various activities related to the systems at the deparment, including demos, MPI-accounts, hardware, etc.
- July 2019 - February 2021:
Student Research Assistant, Max-Planck-Institut für Informatik, Saarland Informatics Campus, Germany
Development, setup and maintenance of Question Answering demos.
- March 2018 - December 2020:
Student Assistant, Cluster of Excellence (MMCI), Saarland Informatics Campus, Germany
Development and maintenance of multiple websites and services that are used by the Saarland Informatics Campus (SIC), including an application portal for SIC internal positions, and a system for organizing the Journalistenpreis Informatik.