Spatio-Temporal Contrastive Learning Enhanced GNNs for Session-based
Recommendation
Abstract
Session-based recommendation (SBR) systems aim to utilize the user’s
short-term behavior sequence to predict the next item without the
detailed user profile. Most recent works try to model the user
preference by treating the sessions as between-item transition graphs
and utilize various graph neural networks (GNNs) to encode the
representations of pair-wise relations among items and their neighbors.
Some of the existing GNN-based models mainly focus on aggregating
information from the view of spatial graph structure, which ignores the
temporal relations within neighbors of an item during message passing
and the information loss results in a sub-optimal problem. Other works
embrace this challenge by incorporating additional temporal information
but lack sufficient interaction between the spatial and temporal
patterns. To address this issue, inspired by the uniformity and
alignment properties of contrastive learning techniques, we propose a
novel framework called Session-based Recommendation with Spatio-Temporal
Contrastive Learning Enhanced GNNs (RESTC). The idea is to supplement
the GNN-based main supervised recommendation task with the temporal
representation via an auxiliary cross-view contrastive learning
mechanism. Furthermore, a novel global collaborative filtering graph
(CFG) embedding is leveraged to enhance the spatial view in the main
task. Extensive experiments demonstrate the significant performance of
RESTC compared with the state-of-the-art baselines e.g., with an
improvement as much as 27.08% gain on HR@20 and 20.10% gain on
MRR@20.