Making sense out of data is a matter of perspective.

Digging deeper ever since. Nerd Face


A long journey of adventures - climbing higher and digging deeper ever since. Be greedy.

After finishing my Master's Degree, I decided to conquer the world going into industry. My work at ALDI has taught & given me so much! · Decisions · Is it still fun? - Totally · Is it demanding (enough)? - Yes · Do you still it? - Very much so · Then why leave?

This was not it (yet) · something was calling for more · the next endeavor. Having spent a very grateful time in Science and Education at COMSYS1, Network Architectures Group2, RWTH Aachen, with Prof. Dr.-Ing. Klaus Wehrle (Klaus)1, Prof. Dr. rer.-nat. Oliver Hohlfeld2, and the family,

further following the White Rabbit, I am now a member of the Computer Networks Group at Brandenburg University of Technology (BTU), located in Cottbus, supervised by Oliver.

Decisions once again soon · Yes · Next venture? let's talk

The walk-through get's you to all exciting places.


  • Computer Networking, Core Internet
  • Computing- & Storage Infrastructure
  • Data, Databases, Big Data
    (data warehousing with ClickHouse)
  • import ray, numpy, pandas, matplotlib, seaborn, scipy, sklearn, networkx, nltk, gensim, nlp, torch, transformers
  • Online Social Networks
  • Empirical Analysis & Visualization, Modeling
  • (Explainable) AI, Machine + Deep Learning
  • Geometric Deep Learning, Information Embedding, Recommender Systems, Natural Language Processing & Generation



  • Secure Scaling Infrastructure
  • Data Engineering · Visualization
  • Analysis · Modeling
  • Deep Learning · Artificial Intelligence
  • Project Management · Acquisition
  • Efficient Knowledge Transfer
  • Supervision
  • Solutions
  • Suitcase · Commitment

Latest News

2022-03PaperCrowdsourcing is hard! I am proud to announce that our content analysis paper on a Social Media platform within Saudi Arabia has been accepted to LocWeb'22 WWW'22 - paper.
2022-01TeachingCongratulations to Max! One of my student’s thesis about user lifetime forecasting in social messaging platforms using machine learning has been awarded Best Faculty’s Bachelor Thesis ‘21 by BTU, Faculty 1 - Mathematics, Computer Science, Physics, Electrical Engineering & Information Technology. Read more in our paper.
2021-12PaperChristmas came early this year: Our recent empirical work about user behavior differences within social messaging platforms comparing much unlike geographic regions has been accepted to PAM'22 - paper.
2021-03PaperFinally, great work with one of my Bachelor students has been successfully presented (paper) at LocWeb'21 WWW'21.
2020-12TeachingOn our University’s ‘Tag der Lehre’ (day of teaching), Oliver presented our approach to teach core internet fundamentals using the ETHZ Mini Internet.

Latest Publications ·

Interpreting Emoji with Emoji: 🏖️ => ☀️😎🌊 · NAACL-HLT Emoji 2022

Workshop on Emoji Understanding and Applications in Social Media at NAACL-HLT 2022

 Jens Helge Reelfs,  Timon Mohaupt,  Sandipan Sikdar,  Markus Strohmaier,  Oliver Hohlfeld


We study the extent to which emoji can be used to add interpretability to embeddings of text and emoji. To do so, we extend the POLAR-framework that transforms word embeddings to interpretable counterparts and apply it to word-emoji embeddings trained on four years of messaging data from the Jodel social network. We devise crowdsourced human judgement experiment to study six use-cases, evaluating against words only, what role emoji can play in adding interpretabil012 ity to word embeddings. That is, we use a revised POLAR approach interpreting words and emoji with words, emoji or both according to human judgement. We find statistically significant trends demonstrating that emoji can be used to interpret other emoji very well.

Characterizing the country-wide adoption and evolution of the Jodel messaging app in Saudi Arabia · JWS 2022

The Journal of Web Science 2022

 Jens Helge Reelfs,  Oliver Hohlfeld,  Markus Strohmaier,  Niklas Henckell


Social media is subject to constant growth and evolution, yet little is known about their early phases of adoption. To shed light on this aspect, this paper empirically characterizes the initial and country-wide adoption of a new type of social media in Saudi Arabia that happened in 2017. Unlike established social media, the studied network Jodel is anonymous and location-based to form hundreds of independent communities country-wide whose adoption pattern we compare. We take a detailed and full view from the operators perspective on the temporal and geographical dimension on the evolution of these different communities—from their very first the first months of establishment to saturation. This way, we make the early adoption of a new type of social media visible, a process that is often invisible due to the lack of data covering the first days of a new network.

Anonymous Hyperlocal Communities: What do they talk about? · WWW LocWeb 2022

International Workshop on Location and the Web at WWW 2022

 Jens Helge Reelfs,  Oliver Hohlfeld,  Niklas Henckell

PDF arXiv DOI slides

In this paper, we study what users talk about in a plethora of independent hyperlocal and anonymous online communities in a single country: Saudi Arabia (KSA). We base this perspective on performing a content classification of the Jodel network in the KSA. To do so, we first contribute a content classification schema that assesses both the intent (why) and the topic (what) of posts. We use the schema to label 15k randomly sampled posts and further classify the top 1k hashtags. We observe a rich set of benign (yet at times controversial in conservative regimes) intents and topics that dominantly address information requests, entertainment, or dating/flirting. By comparing two large cities (Riyadh and Jeddah), we further show that hyperlocality leads to shifts in topic popularity between local communities. By evaluating votes (content appreciation) and replies (reactions), we show that the communities react differently to different topics; e.g. entertaining posts are much appreciated through votes, receiving the least replies, while beliefs & politics receive similarly few replies but are controversially voted.
more ·




Jens Helge Reelfs Photo

Helge Reelfs
Brandenburg University of Technology
Chair of Computer Networks
Konrad-Wachsmann-Allee 5
03046 Cottbus, Germany
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My Group
Chair of Computer Networks
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