Asymmetric Query Expansion

Definition

Asymmetric Query Expansion

Asymmetric query expansion maps a query word form to a set of forms to search for. Matching is directional: need not imply .

Comparison with Normalisation

Matching through a shared normalisation function is symmetric: also gives . Query expansion can instead choose different alternatives for each query form. Searching several alternatives can require more query-processing work than looking up a single normalised form.

Example

Preserving a capitalised name

A system could use the following expansion sets:

The lowercase query windows includes the product name Windows, but the capitalised query Windows searches only for that name: