GLIMPSE
GLIMPSE is a text indexing and retrieval software program originally developed at the University of Arizona by Udi Manber, Sun Wu, and Burra Gopal. It was released under the ISC open source license in September 2014.
GLIMPSE stands for GLobal IMPlicit SEarch. While many text indexing schemes create quite large indexes (usually around 50% of the size of the original text), a GLIMPSE-created index is only 2-4% of the size of the original text.