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Item Cluster-aware Prompt Learning for Session-based Recommendation

Wooseong Yang, Chen Wang, Zihe Song, Weizhi Zhang, Philip S. Yu

TL;DR

CLIP-SBR addresses the limitation of relying solely on intra-session item relations in session-based recommendation by introducing a two-module framework: a global item relationship graph with Leiden-based clustering to capture inter-session connections, and cluster-aware soft prompts that are integrated into SBR training. By unifying intra- and inter-session interactions and injecting cluster-specific cues, it provides a universal, efficient mechanism to enhance diverse SBR models. Empirical results across three real-world datasets and eight baselines show consistent performance gains and reduced training time, validating the approach's practicality. This work advances SBR by enabling scalable cross-session knowledge transfer through prompt learning on item communities.

Abstract

Session-based recommendation (SBR) aims to capture dynamic user preferences by analyzing item sequences within individual sessions. However, most existing approaches focus mainly on intra-session item relationships, neglecting the connections between items across different sessions (inter-session relationships), which limits their ability to fully capture complex item interactions. While some methods incorporate inter-session information, they often suffer from high computational costs, leading to longer training times and reduced efficiency. To address these challenges, we propose the CLIP-SBR (Cluster-aware Item Prompt learning for Session-Based Recommendation) framework. CLIP-SBR is composed of two modules: 1) an item relationship mining module that builds a global graph to effectively model both intra- and inter-session relationships, and 2) an item cluster-aware prompt learning module that uses soft prompts to integrate these relationships into SBR models efficiently. We evaluate CLIP-SBR across eight SBR models and three benchmark datasets, consistently demonstrating improved recommendation performance and establishing CLIP-SBR as a robust solution for session-based recommendation tasks.

Item Cluster-aware Prompt Learning for Session-based Recommendation

TL;DR

CLIP-SBR addresses the limitation of relying solely on intra-session item relations in session-based recommendation by introducing a two-module framework: a global item relationship graph with Leiden-based clustering to capture inter-session connections, and cluster-aware soft prompts that are integrated into SBR training. By unifying intra- and inter-session interactions and injecting cluster-specific cues, it provides a universal, efficient mechanism to enhance diverse SBR models. Empirical results across three real-world datasets and eight baselines show consistent performance gains and reduced training time, validating the approach's practicality. This work advances SBR by enabling scalable cross-session knowledge transfer through prompt learning on item communities.

Abstract

Session-based recommendation (SBR) aims to capture dynamic user preferences by analyzing item sequences within individual sessions. However, most existing approaches focus mainly on intra-session item relationships, neglecting the connections between items across different sessions (inter-session relationships), which limits their ability to fully capture complex item interactions. While some methods incorporate inter-session information, they often suffer from high computational costs, leading to longer training times and reduced efficiency. To address these challenges, we propose the CLIP-SBR (Cluster-aware Item Prompt learning for Session-Based Recommendation) framework. CLIP-SBR is composed of two modules: 1) an item relationship mining module that builds a global graph to effectively model both intra- and inter-session relationships, and 2) an item cluster-aware prompt learning module that uses soft prompts to integrate these relationships into SBR models efficiently. We evaluate CLIP-SBR across eight SBR models and three benchmark datasets, consistently demonstrating improved recommendation performance and establishing CLIP-SBR as a robust solution for session-based recommendation tasks.
Paper Structure (24 sections, 9 equations, 3 figures, 3 tables, 1 algorithm)

This paper contains 24 sections, 9 equations, 3 figures, 3 tables, 1 algorithm.

Figures (3)

  • Figure 1: The proposed CLIP-SBR framework consists of two main modules. The Item Relationship Mining module constructs session graphs and combines them into a global graph to capture intra- and inter-session item relationships, followed by community detection to identify item clusters. The Item Cluster-aware Prompt Learning module enhances SBR models by integrating learnable soft prompts tailored to these clusters, embedding cluster-specific information to improve recommendation accuracy and efficiency.
  • Figure 2: Improvement (%) comparison of CLIP-SBR variants on the three datasets. The blue bar represents the original CLIP-SBR, while the other colors indicate various CLIP-SBR variants. "Avg. Improv." refers to the average of improvement percentage calculated from MRR@5 and Recall@5.
  • Figure 3: Performance comparison of CLIP-GRU4Rec with different resolution parameters on the three datasets. The MRR@5 scale for Last.fm and Xing is shown on the left y-axis, while the scale for Reddit is on the right y-axis.