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"boolean and: separate words by space e.g., codd modelboolean or: connect words by pipe symbol (|) e.g., graph|networkUpdate May 7, 2017: Please note that we had to disable the phrase search operator (.) and the boolea