2001--Stanley Kubrick's epic of human advancement, externally motivated. The special effects must be seen, and can best be seen from the first five rows. At the CINERAMA, Washington Street near Essex (482-4515).

West Side Story--Much, much worse than the show. Badly dubbed and drippily sung, but funny in places. At the SAVOY, 163 Tremont (536-2120).

Whatever Hapepned to Baby Jane?-- Bette Davis and Joan Crawford play weird sisters in this debatably entertaining second-rate Robert Aldrich picture, marred by overly loud music and weak script construction. At M.I.T., Sunday night.

Yellow Submarine--A good cartoon about the Beatles not to be confused either with The Road Runner or Joyce's Ulysses. The drawing art, but the 85 minutes are provocative and occasionally moving. At the BEACON HILL, Tremont between Beacon St. & ovt. Center (227-6676).

You Are What You Eat--A tedious romp with Tiny Tim and friends that is much less fun than Beach Party. At the KEN-more, Kenmore Square (262-3799).

Young Girls of Rochefort -- Jacques (Lola, Umbrellas of Cherbourg) Demy's fabulous Cinemascope musical with a great Michel Legland score and the cast of the year: Catherine Deneuve and Francoise Dorleac pursued by Gene Kelly (looking a young 35) and Jacques Perrin, while Michel Piccoli and Danielle Darieux watch from the wings. The color photography radiates day-light and Demy steadfastly resists all but the joyful aspects of romance