Gnod is an experiment in artificial intelligence. It “learns” from input users supply. Ultimately, the program “understands” relationships—between musicians, books, movies—and can predict similarities or differences. For example, the “gnoosic” section asks users to enter three musical artists they already like. The program then lists other artists and asks users to indicate whether they like, don’t like or don’t know each. Soon, it learns your tastes and leads you to new stuff. Especially interesting is the “map” feature, which, in the “gnook” section, places Toni Morrison fairly close to Alice Walker (expected), Jonathan Lethem (unexpected) and Willa Cather (extremely unexpected). It’s an intriguing way to discover relationships, however strange, between artists you admire.