Fall season at “City Ballet” (among those in the know, short for New York City Ballet) contains six different programs. “All Balanchine I” is a beaut, with ballets to Mozart (Divertimento No. 15), Mendelssohn (Scotch Symphony), and Vittorio Rieti’s weaving of themes from Bellini’s operas (La Sonnambula), all containing beautiful duets. The strangest and most inventive of these duets is found in La Sonnambula. It’s the dance between a handsome poet and a mysterious sleepwalker that plays out as a haunting Euclidean game, touched with eros. The “All Stravinsky” program shows the range of Igor Stravinsky’s presence in the NYCB repertory, his power as a sort of Russian godfather to both George Balanchine and Jerome Robbins. Check the company Web site for dates. —Laura Jacobs