Multiview Identifiers Enhanced Generative Retrieval (2023)

Abstract: Instead of simply matching a query to pre-existing passages, generative retrieval generates identifier strings of passages as the retrieval target. At a cost, the identifier must be distinctive enough to represent a passage. Current approaches use either a numeric ID or a text piece (such as a title or substrings) as the identifier. However, these identifiers cannot cover a passage’s content well. As such, we are motivated to propose a new type of identifier, synthetic identifiers, that are generated based on the content of a passage and could integrate contextualized information that text pieces lack. Furthermore, we simultaneously consider multiview identifiers, including synthetic identifiers, titles, and substrings. These views of identifiers complement each other and facilitate the holistic ranking of passages from multiple perspectives. We conduct a series of experiments on three public datasets, and the results indicate that our proposed approach performs the best in generative retrieval, demonstrating its effectiveness and robustness.

## introduction text retrieval is a fundamental task in information retrieval and plays a vital role in various language systems, including search ranking @xcite and open-domain question answering @xcite . in recent years, the dualencoder approach @xcite , which encodes queries/passages into vectors and matches them via the dot-product operation, has been the de-facto implementation. however, this approach is limited by the embedding space bottleneck @xcite and missing fine-grained interaction @xcite . an emerging alternative to the dual-encoder approach is generative retrieval @xcite @xcite . generative retrieval utilizes autoregressive language query: who is the singer of does he love you? passage ( https://en.wikipedia.org/wiki/does_he_love_you ) "does he love you" is a song written by sandy knox and billy stritch, and recorded as a duet by american country music artists reba mcentire and linda davis. it was released in august 1993 as the first single from reba's album "greatest hits volume two". it is one of country music's several songs about a love triangle. "does he love you" was written in 1982 by billy stritch. ...... ## method given a query text q, the retrieval system is required to retrieve a list of passages p 1 , p 2 , . . . , p n , from a corpus c. both queries and passages are a sequence of text tokens. besides, there are k relevant querypassage pairs {q i , p i } k for training, where p @xmath0. ## conclusion and future work in this work, we present minder, a novel retrieval system that combines an autoregressive language 6643 model with multiview identifiers. we find pseudoqueries are admirable identifiers that could work on different search scenarios. more importantly, minder simultaneously utilizes multiple types of identifiers, including titles, substrings, and pseudoqueries. these different views of identifiers could complement each other, which makes minder effective and robust in different search scenarios. the experiments on three widely-used datasets illustrate minder achieves the best performance in generative retrieval. in the future, we aim to improve minder from the following aspects.minder adopts a heuristic function to aggregate predicted identifiers and rank passages. the heuristic rank function relies on manual hyper-parameters to balance different views of identifiers, which may not be suitable for all samples. as such, we are motivated to integrate the rank process into an auto-learned neural network. besides, we plan to apply minder on more search domains, like the few-shot retrieval setting. for better reproduction, we detail the training hyperparameters in