Our search engine supports the following operators:

+: A leading plus sign indicates that this word must be present in every row returned.
-: A leading minus sign indicates that this word must not be present in any row returned.
: By default (when neither a plus or minus sign is specified) the word is optional, but the rows that contain it will be rated higher.; These two operators are used to change a word's contribution to the relevance value that is assigned to a row. The < operator decreases the contribution and the > operator increases it. See the example below.
( ): Parentheses are used to group words into subexpressions.
~: A leading tilde acts as a negation operator, causing the word's contribution to the row relevance to be negative. It's useful for marking noise words. A row that contains such a word will be rated lower than others, but will not be excluded altogether, as it would be with the - operator.
*: An asterisk is the truncation operator. Unlike the other operators, it should be appended to the word, not prepended.

And here are some examples:

apple banana: find rows that contain at least one of these words.
+apple +juice: ... both words
+apple macintosh: ... word ``apple'', but rank it higher if it also contain ``macintosh''
+apple -macintosh: ... word ``apple'' but not ``macintosh''
+apple +(>pie <strudel): ... ``apple'' and ``pie'', or ``apple'' and ``strudel'' (in any order), but rank ``apple pie'' higher than ``apple strudel''.
apple*: ... ``apple'', ``apples'', ``applesauce'', and ``applet''