Up to a certain point, cinematic puzzles can be fascinating. They reel you in as your mind goes into overdrive and you desperately try to understand who is deceiving who. Still, a puzzle that lasts too long grows tedious, especially if it teases the possibility of a solution. Certified Copy nearly belongs in the latter category, yet it’s saved by phenomenal performances and intriguing on-screen chemistry. Writer/director Abbas Kiarostami keeps audiences guessing well beyond the point of emotional investment, so his thoughtful slice-of-life story works better as a thought experiment.