小模型通过融合检索与生成推理,实现对未见问题的泛化回答。
Teaching Smaller Language Models To Generalise To Unseen Compositional Questions (Full Thesis)
- 用检索和生成双源知识增强小模型推理能力
- 新数据集使小模型在未见问题上准确率显著提升
- 适合资源受限场景下的智能问答系统
预训练的大语言模型(LLMs)能回答训练中未见过的问题。但在延迟、成本、算力和网络连接受限的场景下,需使用更小的推理模型。本文研究在本地计算资源有限、无网络连接条件下,小模型如何应对未知分布的任意问题。通过引入两种知识来源:基于多跳密集检索系统的维基百科语料,以及在低资源环境下优化的大型模型生成的推理链。提出新方法,使小模型无需记忆即可回答上下文相关问题。建立了一套完整的未见数据集基准测试结果。实验表明,在训练中加入新型检索增强训练数据集(RATD)可显著提升性能;进一步结合双源知识的方法(RR)通过新设计的推理链排序模型,对生成与检索内容进行相关性与真实性评分,构建综合上下文,带来更大提升。还证明小模型能有效利用噪声混合上下文。
原文摘要 · Abstract (English)
Pretrained large Language Models (LLMs) are able to answer questions that are unlikely to have been encountered during training. However a diversity of potential applications exist in the broad domain of reasoning systems and considerations such as latency, cost, available compute resource and internet connectivity are relevant in determining an appropriate approach. We consider the setting where some local compute capacity is available at inference time but internet connectivity is not. Similar to a general-purpose LLM, we assume that our much smaller Reasoning Models may be asked arbitrary questions from unknown distributions, so we focus on evaluation in an unseen setting. We train our models to answer diverse questions by instilling an ability to reason over a retrieved context. We acquire context from two knowledge sources; a Wikipedia corpus queried using a multi-hop dense retrieval system with novel extensions, and from rationales generated from a larger Language Model optimised to run in a lower resource environment. Our main contributions: We propose novel methods to show that our model is capable of answering contextualised questions without memorisation. We establish a comprehensive set of baseline results on unseen evaluation datasets. We show that the addition of novel retrieval-augmented training datasets (RATD) to the training regime of the Reasoning Model significantly improves results. We demonstrate further significant improvement through the application of methods for combining knowledge from two sources. The first method (RR) involves training a novel Rationale Ranking model to score both generated rationales and retrieved contexts with respect to relevance and truthfulness. We use the scores to derive combined contexts. We also show that utilising the RATD datasets enables our model to become proficient at utilising combined noisy contexts.
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