# Data structuring

> The shape of the data before a ranker runs. Vector search and lexical tagging sit under this subject. The structure decides what close is allowed to mean.

Broader subject: [Relevance](https://oppority.com/topics/relevance.md).

## Within this subject

- [Vector search](https://oppority.com/topics/vector-search.md): Search by nearest neighbor in an embedding space. I am studying when a dense signal helps, and when a precise lexical handle should outrank it.
- [Lexical tagging](https://oppority.com/topics/lexical-tagging.md): Tokens, entities, and tags taken from the text itself, including tags extracted with classical tools or with a language model. A label a person can read, used as a handle for lexical retrieval.