Question: Showboat World, written in 1975, is the second, stand-alone novel in a pair of science fiction novels by Jack Vance, was an American mystery, fantasy, and science fiction writer, he also wrote how many mystery novels, under the pseudonym Ellery Queen?
Sentence (from "Avram Davidson"): Avram Davidson (April 23, 1923 – May 8, 1993) was an American writer of fantasy fiction, science fiction, and crime fiction, as well as the author of many stories that do not fit into a genre niche.
Relevant evidence: No