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Petra Kralj Novak

PhD, researcher at the Department of Knowledge Technologies, Jožef Stefan Institute

Short CV

I am a researcher at the Department of Knowledge Technologies, Jožef Stefan Institute, Ljubljana, Slovenia. My research belongs to the wide area of knowledge discovery from databases. Currently, as a postdoctoral researcher, I analyse social and mainstream media focusing on the mediated sentiment and hate speech. Avant-garde research in analyzing the role of emojis in conveying sentiment was published in P. Kralj Novak, et al. "Sentiment of emojis" and is the main reference for current research in the analysis of emoji. I publish research papers and datasets in top academic venues.

My thesis focused on rule induction from class labeled data, where the induced rules are intended for human interpretation. The main findings of the thesis are published in Journal of Machine Learning Research and in the Encyclopedia of Machine Learning. I also designed and implemented GMOtreck - a system for optimization of laboratory level traceability of genetically modified organisms. I regularly serve in program committees of major academic and industrial conferences such as ICDM, ICML, DS, IDA, and Southern Data Science. I am PC co-chair of the 22nd International Conference on Discovery Science (2019, Split, Croatia). From 2006 to 2009, and from 2018 on I am secretary and treasurer of SLAIS - the Slovenian Artificial Intelligence Society. I have also actively collaborated in several national and European research projects. I am the coordinator of the EU REC AG project IMSyPP: Innovative Monitoring Systems and Prevention Policies of Online Hate Speech (2020-2022).

I have given seminars and invited talks to diverse audiences. These include academic (e.g., Georgia State University [USA], Ca'Foscari University of Venice [Italy], Fudan University [China], University of Ljubljana [Slovenia]) and industrial audiences (Southern Data Science [USA], Career Builder, LLC [USA], Facebook [Italy]). I was keynote at scientific conferences CMC Corpora 2016 and DS 2019. I have also taught several data mining related courses at undergraduate and graduate level at the Jožef Stefan International Postgraduate School, at University of Nova Gorica, Slovenia, and at the Faculty of Information studies Novo mesto, Slovenia.



  • Tackling hate speech on Slovenian Twitter: invited talk at Language Technology vs. Disinformation, organized by DG Connect, November 24, 2020
  • Complex Networks with Texts, NetSci2020 school, September 17, 2020
  • Sentiment and stance analysis of social media : invited talk at Data and Complexity Day @Ca'Foscari Conference, November 12, 2018, Venice, Italy.
  • Social media stance mining applications : invited talk at Southern Data Science Conference, April 14, 2018, Atlanta, GA, USA.
  • Deep learning for natural language sentiment and affect: tutorial at ECML PKDD 2018, September 14th, 2018, Dublin, Ireland.
  • Social media stance mining applications : invited talk at Southern Data Science Conference, October 18, 2018, Orlando, Florida, USA.
  • Emojis, sentiment and stance in social media : invited talk at 21st International Conference, DS 2018 Limassol, Cyprus, October 29-31, 2018.
  • Sentiment of emojis : invited talk at the 4th Conference on CMC and Social Media Corpora for the Humanities, 27-28 September 2016, Ljubljana, Slovenia.

Selected publications ( Google Scholar | COBISS)

  • Petra Kralj Novak, Jasmina Smailović, Borut Sluban, Igor Mozetič
  • Sentiment of Emojis
  • PLoS ONE 10(12): e0144296, doi:10.1371/journal.pone.0144296, 2015
  • Fabiana Zollo, Petra Kralj Novak, Michela Del Vicario, Alessandro Bessi, Igor Mozetič, Antonio Scala, Guido Caldarelli, Walter Quattrociocchi
  • Emotional dynamics in the age of misinformation
  • PLoS ONE 10(9): e0138740. doi:10.1371/journal.pone.0138740, 2015