When a film such as Paul Haggis’ Crash wins Best Picture, you know the ensemble formula is officially popular enough to prop up any pile of ham-fisted pap. OK, we get it: A dozen or so unconnected people’s lives will become intertwined and forever altered by a series of events thrown into motion by one innocent coincidence, and before the credits roll, each will get his own shot at redemption. Even Robert Altman—the man who practically invented the ensemble film and the subject of AFI’s “Robert Altman: American Original” retrospective—should know that the genre’s only good for one or two quality films a decade, tops. Altman initially made his mark 36 years ago with M*A*S*H, a black comedy about a group of oddball field surgeons set during the Korean War, and 1975’s Nashville (pictured), which tracks 24 different characters at a political rally and concert in Music City. Following a string of mediocre films in the ’80s, he returned with 1992’s stinging Hollywood satire The Player and 1993’s langorously lush ensemble job Short Cuts; the 2001 British whodunit Gosford Park did the same trick for the director after the dry spell that followed those films’ acclaim. Keep an eye out for Haggis, Aric Avelino, and the next generation of Altman-wannabes in the audience when “Robert Altman: American Original” opens Friday, May 26, and runs through Thursday, July 6 (see Showtimes for a weekly schedule), at the American Film Institute’s Silver Theatre and Cultural Center, 8633 Colesville Road, Silver Spring. $9.25. (301) 495-6720. (Matthew Borlik)