A counterfactual collaborative session-based recommender system

Wenzhuo Song, Shoujin Wang, Yan Wang, Kunpeng Liu, Xueyan Liu*, Minghao Yin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference proceeding contributionpeer-review

3 Citations (Scopus)


Most session-based recommender systems (SBRSs) focus on extracting information from the observed items in the current session of a user to predict a next item, ignoring the causes outside the session (called outer-session causes, OSCs) that influence the user's selection of items. However, these causes widely exist in the real world, and few studies have investigated their role in SBRSs. In this work, we analyze the causalities and correlations of the OSCs in SBRSs from the perspective of causal inference. We find that the OSCs are essentially the confounders in SBRSs, which leads to spurious correlations in the data used to train SBRS models. To address this problem, we propose a novel SBRS framework named COCO-SBRS (COunterfactual COllaborative Session-Based Recommender Systems) to learn the causality between OSCs and user-item interactions in SBRSs. COCO-SBRS first adopts a self-supervised approach to pre-train a recommendation model by designing pseudo-labels of causes for each user's selection of the item in data to guide the training process. Next, COCO-SBRS adopts counterfactual inference to recommend items based on the outputs of the pre-trained recommendation model considering the causalities to alleviate the data sparsity problem. As a result, COCO-SBRS can learn the causalities in data, preventing the model from learning spurious correlations. The experimental results of our extensive experiments conducted on three real-world datasets demonstrate the superiority of our proposed framework over ten representative SBRSs.

Original languageEnglish
Title of host publicationThe ACM Web Conference 2023
Subtitle of host publicationproceedings of the World Wide Web Conference WWW 2023
Place of PublicationNew York
PublisherAssociation for Computing Machinery (ACM)
Number of pages12
ISBN (Electronic)9781450394161
Publication statusPublished - 2023
EventACM Web Conference 2023 (32nd : 2023) - Austin, United States
Duration: 30 Apr 20234 May 2023
Conference number: 32


ConferenceACM Web Conference 2023 (32nd : 2023)
Country/TerritoryUnited States


  • session-based recommendation
  • self-supervised learning
  • counterfactuals


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