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Call: ACM RecSys 2021 - RecSys Challenge 2021

Wednesday, June 23, 2021

Event Details

For the online version of this Call, visit: 

The RecSys Challenge 2021 will be organized by Politecnico di Bari, ETH Zürich, Jönköping University, and the data set will be provided by Twitter. The challenge focuses on a real-world task of tweet engagement prediction in a dynamic environment. For 2021, the challenge considers four different engagement types: Likes, Retweet, Quote, and replies. This year’s challenge brings the problem even closer to Twitter’s real recommender systems by introducing latency constraints. We will also increase the data size to encourage novel methods. Also, the data density will be increased in terms of the graph where users are considered to be nodes and interactions as edges.

The goal is twofold: to predict the probability of different engagement types of a target user for a set of tweets based on heterogeneous input data while providing fair recommendations. We are conscious that multi-goal optimization considering accuracy and fairness will be particularly challenging. However, we believe that the recommendation community is nowadays mature enough to face the challenge of providing accurate and, at the same time, fair recommendations.

A detailed description of the challenge is available on the website of the RecSys Challenge 2021:

Accepted contributions will be presented during the RecSys Challenge 2021 Workshop.


*Walter Anelli, Politecnico di Bari, Italy
*Saikishore Kalloori, ETH Zürich, Switzerland
*Bruce Ferwerda, Jönköping University, Sweden


*Luca Belli, Twitter
*Michael Bronstein, Twitter
*Alexandre Lung-Yut-Fong, Twitter
*Ben Chamberlain, Twitter
*Frank Portman, Twitter
*Alykhan Tejani, Twitter
*Yuanpu Xie, Twitter
*Jj Hunt, Twitter
*Wenzhe Shi, Twitter


*Gabriele Sottocornola, Free University of Bozen-Bolzano, Italy
*Amra Delic, TU Wien, Austria & University of Sarajevo, Bosnia and Herzegovina
*Jessie Smith, University of Colorado, Boulder
*Nazareno Andrade, Universidade Federal de Campina Grande, Brazil