Cleo, the pseudonymous Stack Exchange mathematician known for solving complex integrals instantly, was revealed in January 2025 to be Vladimir Reshetnikov, an Uzbekistani-American software developer. Active from 2013 to 2015, Cleo posted 39 precise answers to advanced integration problems without showing any intermediate steps. The account claimed to be female and cited a medical condition limiting long-form communication.
The speed and accuracy of the solutions sparked debate over whether Cleo was an individual genius or a collective system. The mathematical community analyzed the answers for patterns, comparing Cleo to historical figures like Srinivasa Ramanujan, who also provided solutions without proofs. The first notable answer came on November 11, 2013, when Cleo solved a difficult integral that had stumped other users, including mathematician Ron Gordon.
Gordon later provided a full proof confirming Cleo’s answer, earning over 1,000 upvotes and the nickname 'Master of Integration.' Despite being correct, Cleo’s responses were controversial for lacking educational value, challenging Stack Exchange’s goal of building a knowledge library. The account’s profile once featured a quote from Ramanujan about visions of elliptic integrals, adding to the mystique. The revelation of Reshetnikov’s identity ended years of speculation but left questions about the nature of his mathematical insight and the role of AI or hidden collaboration.
Source: Hacker News · Summarized by HeadlinesBriefing