核心概念
PEARLM, a novel approach that captures user behaviour and product-side knowledge through language modelling, directly learns knowledge graph embeddings from paths over the knowledge graph, unifying entities and relations in the same latent space, and introduces constraints on the sequence decoding to guarantee path faithfulness, outperforming state-of-the-art baselines in recommendation utility, coverage, novelty, and serendipity.
要約
The paper introduces PEARLM, a novel approach for explainable recommendation systems that leverages language modelling to capture user behaviour and product-side knowledge. The key innovations of PEARLM are:
- Direct learning of token embeddings from knowledge graph (KG) paths, bypassing the need for pre-trained embeddings.
- A unified approach in token prediction for both entities and relations.
- The introduction of KG-constrained sequence decoding to ensure the authenticity of the generated paths.
The authors first conduct an empirical study on hallucination in KG-based explainable recommendation systems, highlighting its effect on user trust and the challenge of detecting inaccuracies.
PEARLM's training involves sampling user-centric paths from the KG and using a causal language model to predict the next token in the sequence. The model's architecture is designed to be sensitive to the sequential flow and hierarchical structure of KG paths, with a tailored 'masked' self-attention mechanism ensuring the generated predictions adhere to the chronological order and logical consistency of the paths.
During inference, PEARLM employs a novel Graph-Constrained Decoding (GCD) method that incorporates KG constraints directly into the sequence generation process, ensuring the resulting paths faithfully represent the actual KG structure.
Comprehensive experiments across MovieLens1M and LastFM1M datasets demonstrate PEARLM's significant improvements in recommendation utility, coverage, novelty, and serendipity compared to state-of-the-art baselines. The authors also analyze the impact of key modelling factors, such as dataset size, path length, and language model size, confirming PEARLM's scalability and effectiveness in various configurations.
統計
PEARLM achieves an NDCG score of 0.44 on MovieLens1M, a 42% improvement over the next best performer KGAT.
On LastFM1M, PEARLM records an NDCG score of 0.59, outperforming the second-best CKE by 78.7%.
PEARLM gains 3.33% in Serendipity on MovieLens1M compared to the second-best model (UCPR) and 19.2% over the third-best (PLM).
On LastFM1M, PEARLM shows a 73% improvement in Coverage over PLM and 47% over CKE.
引用
"PEARLM's depth-centric exploration approach crafts detailed embeddings, capturing intricate graph relationships. This results in significantly enhanced performance in the recommendation downstream task compared to neighbour-focused approaches."
"PEARLM's results reveal an integration of the best attributes from both path reasoning and knowledge-aware models. It consistently delivers performance that is either superior or, at the very least, comparable to top-performing models across key metrics."