About me

My name is Szymon Chojnacki. I am an assistant professor at the Insitute of Computer Science of the Polish Academy of Sciences. I work with the Foundations of Artificial Intelligence Group under the supervision of Mieczyslaw Klopotek. I am interested in techniques with sound mathematical foundations. My most recent activity comprises three topics:

  • recommender systems
  • big data
  • computer graphics


I teach Mining massive datasets within Interdisciplinary PhD Studies in IPIPAN. Visit informal course website.

This fall I recorded a video version of Mining massive datasets. You can join studying via e-learning track. Please watch a sample video

Book Acknowledgment

New book about text processing authored by Grant Ingersoll is ready.

I was lucky to contribute (together with Tim Potter) a few pages to Taming Text. We were invited to evaluate Mahout's clustering algorithms on a corpus of all emails ever sent to Apache forums. The computation architecture was sponsored by Amazon Web Services. If you wish to learn more about this short, but busy project please visit our public communication channel.

ECML-PKDD Challenge

Real life tag recommending webservice for www.BibSonomy.org. The system was developed gradually during ECML/PKDD Discovery Challenge 2009.

1. We started with the 16th position during the ofline task [statistics], [proceedings].
2. We improved during the online task and were placed on the 5th position according to f-measure (system no. 13).
3. We managed to outperform other systems during the 6 months Challenge's aftermath period in terms of latency and clickability. (system no. 13).

The optimization techinques responsible for the latency are available in [IEEE Explore].
The improvement from incremental learning techniques is described in [Studia Informatica].


Szymon Chojnacki
Institute of Computer Science PAS
ul. J.K. Ordona 21
room 103
01-237 Warsaw
(+48 22) 836 28 41