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The math problem Jeanne introduces in class is the Collatz Conjecture. The Collatz conjecture is an algorithm that produces the number 1 out of any positive integer by dividing even numbers by 2 and multiplying odd numbers by 3 and adding 1. The result will eventually produce 1. The conjecture is later allegorically reflected in the film's climax when Simon asks Jeanne whether 1 and 1 can make 1, referencing the incest inherent in their parentage. The two people Simon and Jeanne have searched for throughout the film, their father and brother, are revealed to be the same person, reinforcing the films theme that all paths lead to one. Commensurate with the Collatz conjecture, two becomes one.
Although Lubna Azabal was 30 at the time of filming, Denis Villeneuve was convinced that the actress could convey the timespan from 18 to her 60s through the skillful use of make-up.
"Incendies" is French for conflagrations (or fires), but the film kept its French title in many countries, including the USA. In many countries, the title translates to "Incendies - The Woman Who Sings".
Although shot in Jordan, the Middle Eastern country in which the film takes place was deliberately left unnamed. Some viewers have noted the word "Palestine" visible on a window in Nawal's school, but the Christian-Muslim conflict would seem to imply the setting is Lebanon, the birthplace of playwright Wajdi Mouawad.
For the location shooting, Denis Villeneuve used a mix of Iraqi and Lebanese crews. He was initially worried that reliving some of the experiences of war would prove too traumatic for them but instead found that they were keen for their stories to be told to the wider world.