Query Formulation
- Boolean operators (AND, OR, NOT) - may or may not have Boolean semantics
- Fielded (author, title, publication date)
- Hierarchical
- Iteration
- NL Query
- Proximity (adjacency, before/after, n words)
- Fuzzy (e.g., single/multiple-char wildcards, soundex, pattern matching)
- Thesaurus Expansion
- Query By Example, Relevance Feedback, Pseudo RF