### 3.4.2: Relation to Boolean Retrieval

Attributes: *A*_{i}:D->{0,1}

*A*_{i}(d)=1if t_{i} occurs in d0otherwise

Query *q=(q*_{1},...,q_{n})

*q*_{i}=1if t_{i} occurs in the query0otherwise

If all terms in the query are connected by
AND: a document is in the result set, if

*A*_{i}(d)=1 i{1,...,n} with q_{i}=1

If all terms are connected by OR: a document is in the result set, if

* i{1,...,n} with q*_{i}=A_{i}(d)=1

This result can be expressed using the inner product of two
vectors:

For vectors containing only 0 and 1 the inner product counts the
number of positions in which both vectors have a 1.

If all terms in the query are connected by
AND: a document is in the result set, if

*w*_{i}·q=q_{i}

If all terms are connected by OR: a document is in the result set, if

*w*_{i}·q>=1

- ANDed queries select only those documents that are most similar to
the query
- ORed queries select all documents that have a similarity larger
than zero
- the similarity can be used to deliver a ranked list of
documents

© 1998 / HTML-Version 17. 11. 1998: R. Ferber