Hi-Gen: Generative Retrieval For Large-Scale Personalized E-commerce Search

Leveraging generative retrieval (GR) techniques to enhance search systems is an emerging methodology that has shown promising results in recent years. In GR, a text-to-text model maps string queries directly to relevant document identifiers (docIDs), so it dramatically simplifies the whole retrieval process. However, when applying most GR models in large-scale E-commerce for personalized item search, we have to face two key problems in encoding and decoding. (1) Existing docID generation methods ignore the encoding of efficiency information, which is critical in E-commerce. (2) The positional information is important in decoding docIDs, while prior studies have not adequately discriminated the significance of positional information or well exploited the inherent interrelation among these positions. To overcome these problems, we introduce an efficient Hierarchical encoding-decoding Generative retrieval method (Hi-Gen) for large-scale personalized E-commerce search systems. Specifically, we first design a representation learning model along with metric learning to learn discriminative feature representations of items to capture both semantic relevance and efficiency information. Then, we propose a category-guided hierarchical clustering scheme that makes full use of the semantic and efficiency information of items to facilitate docID generation. Finally, we design a position-aware loss to discriminate the importance of positions and mine the inherent interrelation between different tokens at the same position. This loss boosts the performance of the language model used in the decoding stage. Besides, we propose two variants of Hi-Gen (i.e.,Hi-Gen-I2I and Hi-Gen-Cluster) to support online real-time large-scale recall in the online serving process. Extensive experiments on both public and industry datasets demonstrate the effectiveness and efficiency of Hi-Gen.

Decomposed Prototype Learning for Few-Shot Scene Graph Generation

Today's scene graph generation (SGG) models typically require abundant manual annotations to learn new predicate types. Thus, it is difficult to apply them to real-world applications with a long-tailed distribution of predicates. In this paper, we focus on a new promising task of SGG: few-shot SGG (FSSGG). FSSGG encourages models to be able to quickly transfer previous knowledge and recognize novel predicates well with only a few examples. Although many advanced approaches have achieved great success on few-shot learning (FSL) tasks, straightforwardly extending them into FSSGG is not applicable due to two intrinsic characteristics of predicate concepts: 1) Each predicate category commonly has multiple semantic meanings under different contexts. 2) The visual appearance of relation triplets with the same predicate differs greatly under different subject-object pairs. Both issues make it hard to model conventional latent representations for predicate categories with state-of-the-art FSL methods. To this end, we propose a novel Decomposed Prototype Learning (DPL). Specifically, we first construct a decomposable prototype space to capture intrinsic visual patterns of subjects and objects for predicates, and enhance their feature representations with these decomposed prototypes. Then, we devise an intelligent metric learner to assign adaptive weights to each support sample by considering the relevance of their subject-object pairs. We further re-split the VG dataset and compare DPL with various FSL methods to benchmark this task. Extensive results show that DPL achieves excellent performance in both base and novel categories.