default search action
- case-insensitive prefix search: default
e.g., sig matches "SIGIR" as well as "signal"
- exact word search: append dollar sign ($) to word
e.g., graph$ matches "graph", but not "graphics"
- phrase search: connect words by a dot (.)
- boolean and: separate words by space
e.g., codd model
- boolean or: connect words by pipe symbol (|)
- boolean not: prepend word by minus sign (-)
e.g., knuth -don