How can multi-hop retrieval potentially increase grounding quality? (E.g., by fetching intermediate facts, can it reduce the chance the model makes something up?)

Multi-hop retrieval improves grounding quality by breaking down complex questions into smaller, sequential steps that require fetching and verifying intermediate facts. Instead of attempting to answer a question in a single step, the system retrieves relevant information iteratively, using each step to build a factual chain. This approach reduces the likelihood of the model “guessing” or inventing unsupported details because every part of the answer must align with retrieved evidence. For example, to answer, “What was the inflation rate in the US when the CEO of Company X was born?” a multi-hop system would first retrieve the CEO’s birth year from a reliable source (e.g., a corporate bio), then query economic datasets for the inflation rate in that specific year. Each step is validated independently, making the final output more trustworthy.

By explicitly requiring intermediate facts, multi-hop retrieval enforces a structured reasoning process that limits gaps in logic. Single-step retrieval systems often struggle with questions requiring connections between disparate data points, leading to answers that rely on assumptions. For instance, a model asked, “Did the inventor of the first electric car also work on renewable energy patents?” might incorrectly assume a link between historical figures without verifying timelines. A multi-hop system would first identify the inventor (e.g., Thomas Parker in the 1880s), then check patent databases for renewable energy contributions during his career. This stepwise verification ensures answers are anchored to specific sources rather than vague associations.

Additionally, multi-hop retrieval improves transparency, making it easier to audit and debug outputs. Developers can trace which documents contributed to each intermediate fact, allowing them to identify errors in retrieval or reasoning. For example, if a system answers, “Which city hosted the Olympics the year the author of Book Y was born?” the intermediate steps (author’s birth year → Olympics host that year) can be individually validated. This granularity helps catch cases where a retrieved document might be outdated or misaligned (e.g., using a birth year from an unverified blog post). By isolating and verifying each hop, the system reduces reliance on the model’s internal biases or knowledge, leading to answers that are more factually consistent and less prone to fabrication.