The star height problem in formal language theory is the question whether all regular languages can be expressed using regular expressions of limited star height, i.e. with a limited nesting depth of Kleene stars. Specifically, is a nesting depth of one always sufficient? If not, is there an algorithm to determine how many are required? The problem was raised by Eggan (1963).
Read more about Star Height Problem: Families of Regular Languages With Unbounded Star Height, Computing The Star Height of Regular Languages
Famous quotes containing the words star, height and/or problem:
“A star was broken
Into the centuries of the child
Myselves grieve now, and miracles cannot atone.”
—Dylan Thomas (1914–1953)
“Much more frequent in Hollywood than the emergence of Cinderella is her sudden vanishing. At our party, even in those glowing days, the clock was always striking twelve for someone at the height of greatness; and there was never a prince to fetch her back to the happy scene.”
—Ben Hecht (1893–1964)
“A serious problem in America is the gap between academe and the mass media, which is our culture. Professors of humanities, with all their leftist fantasies, have little direct knowledge of American life and no impact whatever on public policy.”
—Camille Paglia (b. 1947)