First and foremost, Alain Resnais' Smoking/No Smoking is a rigorous exercise in structure, a two-part, "interactive" story that begins with a woman's decision to smoke or not to smoke, then splits off into a total of 12 possible conclusions, six per film. Like a high-minded Choose Your Own Adventure book, the viewer circles back to certain points in the story when a single altered line or action changes the characters' fate. These "what if" film scenarios have become all too commonplace in the last few years, but they usually involve a single person's life forking in two directions (Sliding Doors, Me Myself I, The Family Man, et al), rather than multiple characters and myriad branches. Made in 1993, Smoking/No Smoking predates this trend by several years, but even if it didn't, Resnais' gamesmanship would still be incomparably sophisticated and challenging. But no matter his skills with a protractor, there are limits to film as architecture, especially over the long haul, when the gorgeous cascading structure—mapped out on paper, it looks like a weeping willow—loses its novelty and precious little nourishment remains. With each part running a little under two and a half hours (277 minutes in all), Smoking and No Smoking can be watched in either order, but due to the diminishing returns, it's common to prefer the first one you see to the second. Based on six of the eight playlets in British farceur Alan Ayckbourn's "Intimate Exchanges," which was originally intended to take place over separate nights, the production is staged on simple, deliberately theatrical backdrops. There are a total of nine characters—five women, four men—and all are played by either Pierre Arditi or Sabine Azéma, who are both remarkably adept at changing personalities as fluidly as their wigs. The major players are alcoholic headmaster Toby Teasdale and his unhappy wife Celia, but their shaky marriage introduces a number of possible romantic partners, including their housekeeper, their caretaker, his best friend, and his best friend's wife. The first scene in both films begins with Celia reaching for a pack of cigarettes, but like the proverbial butterfly flapping its wings, her decision to light up impacts the remaining course of her life. Smoking/No Smoking splinters into numerous fragments over time, following paths that are perfectly sectioned in fives—five days, five weeks, and five years. Perhaps best known for his French New Wave classics Hiroshima, Mon Amour and Last Year At Marienbad, Resnais again proves his mastery of mind-bending puzzle structures, but form comes at the content's expense. Though disarmingly light and playful in tone, with moments of genuine humor and feeling, Smoking/No Smoking has a perfunctory attitude toward its characters that slowly creeps to the fore. Within its lovely blueprint, Resnais' project seems curiously uninhabited.