The Last Theorem

The Last Theorem is a science fiction novel by Arthur C. Clarke and Frederik Pohl, published in 2008.

The book is about a young Sri Lankan mathematician, Ranjit Subramanian, who finds a short proof of Fermat's Last Theorem, and about the arrival of an alien force on Earth at the same time. Ranjit's life takes him from Colombo to a research career and into the projects that human governments build in response to the visitors, and the novel follows what the world does with a discovery that has no immediate use and with an invasion that nobody can negotiate with. It was the last novel Clarke published: he began it, and when illness and writer's block stopped him from finishing, he handed his notes to Pohl, who completed it in consultation with him and sent back the manuscript for his approval.

Clarke spent the last decades of his life in Sri Lanka, and the setting of the book comes from that. Pohl had been writing science fiction since the 1930s, and the collaboration was the last one Clarke worked on.