No comprehensive review or survey papers focused explicitly on multi-document question answering (MDQA) from 2020 onwards were found.

While none of the retrieved references are comprehensive review papers on MDQA, some relevant research papers discuss advanced MDQA techniques and models, such as knowledge graph prompting [1], hierarchical contextual augmentation [2], and cross-document QA [3]. Additionally, there are related works on query-focused multi-document summarization [5, 6], which are somewhat relevant but do not fully serve as comprehensive surveys on MDQA.

The most important categories to highlight are comprehensive survey or review papers explicitly focused on multi-document question answering (MDQA) and those closely related to MDQA, followed by papers that provide insights into tasks and methodologies adjacent to MDQA, such as multi-document summarization or complex QA. These categories ensure clarity on which papers directly address the core topic and which offer relevant, useful background information.

1. Comprehensive Review Papers on MDQA (2020 onwards)

   • Description: Survey papers providing a detailed review of techniques, challenges, and advancements in MDQA.
   • References: [none in list]

2. Papers on Advanced MDQA Techniques and Models

   • Description: Research papers discussing state-of-the-art MDQA frameworks, methodologies, and specific advancements post-2020.
   • References: [1, 2, 3, 4]

3. Related Papers on Query-Focused Multi-Document Summarization

   • Description: Papers covering query-focused multi-document summarization, which is closely related to MDQA.
   • References: [5, 6, 8, 14, 15]

4. General Surveys on Question Answering and QA Techniques

   • Description: Broad reviews on question answering methodologies and techniques that touch upon, but do not focus exclusively on, MDQA.
   • References: [7, 11, 13, 16, 17]