"The petition follows months of trepidation about the congress within the math community. “You do not get 1,500 signatures in 10 days without having many, many mathematicians already registering their complaints to their professional societies and to the ICM organizers,” says Ila Varma, a mathematician at the University of Toronto and one of the petition’s co-authors."

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ICM's peak attendance is around four thousand, so 1,500 would-be attendees signing a petition to move the conference in ten days is pretty authoritative.