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<https://discovery.ucl.ac.uk/id/eprint/10192104> <http://purl.org/dc/terms/title> "Towards Generalized Open Domain Question Answering Systems"^^<http://www.w3.org/2001/XMLSchema#string> .
<https://discovery.ucl.ac.uk/id/eprint/10192104> <http://purl.org/ontology/bibo/abstract> "Generalization remains a paramount yet unresolved challenge for open-domain question answering (ODQA) systems, impeding their capacity to adeptly handle novel queries and responses beyond the confines of their training data. This thesis conducts a comprehensive exploration of ODQA generalization.\r\nWe commence with a meticulous investigation into the underlying challenges. Drawing upon studies on systematic generalization, we introduce and annotate questions according to three categories that measure different levels and kinds of generalization: training set overlap, compositional generalization and novel-entity generalization. When evaluating six popular parametric and non-parametric models, we find non-parametric models demonstrate proficiency with novel entities but encounter difficulties with compositional generalization. Noteworthy correlations emerge, such as a positive association between question pattern frequency and test accuracy, juxtaposed with a strong negative correlation between entity frequency and test accuracy, attributable to closely related distractors. Factors influencing generalization include cascading errors originating from the retrieval component, question pattern frequency, and entity prevalence.\r\nBuilding on these insights, the focus pivots towards the enhancement of passage retrieval. We propose a novel contextual clue sampling strategy using language models to address the vocabulary mismatch challenge in lexical retrieval for ODQA. This two-step method, comprising filtering and fusion, generates a diverse set of query expansion terms, yielding retrieval accuracy similar to dense methods while notably reducing the index size.\r\nThe subsequent phase concentrates on refining reader models in ODQA through flat minima optimization techniques, incorporating Stochastic Weight Averaging (SWA) and Sharpness Aware Minimization (SAM). Rigorous benchmarking under- scores the impact of dataset characteristics and model architecture on optimizer effectiveness, with SAM particularly excelling in Natural Language Processing tasks. The combination of SWA and SAM yields additional gains, underscoring the pivotal role of flatter minimizers in fostering enhanced generalization for reader models in ODQA."^^<http://www.w3.org/2001/XMLSchema#string> .
<https://discovery.ucl.ac.uk/id/eprint/10192104> <http://purl.org/dc/terms/date> "2024-05-28" .
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