Vladimir Reshetnikov, born in 1979, is a software developer and mathematician from Uzbekistan and the United States. He became known for answering difficult mathematical questions about integration with high accuracy, without showing any steps, under the secret name Cleo. People online discussed whether Cleo was one person or a group working together.
During Cleo’s active time, he answered 39 advanced math questions, mostly about complex integration problems that had confused other users. His answers were always correct, but he rarely explained how he solved them. He often posted solutions within hours of the questions being asked. The account mentioned that the person had limited interaction due to a medical condition that was not fully explained.
The mystery about Cleo’s identity and math skills interested many in the math community. Some users tried to find clues by studying patterns in his answers and writing style. A few compared Cleo to famous mathematicians like Srinivasa Ramanujan, who also provided solutions without traditional proofs. In January 2025, it was announced that Cleo was Vladimir Reshetnikov.
History
Cleo's mathematics Stack Exchange (Math.SE) profile showed her as a female mathematician with a medical condition that made it hard for her to participate in long discussions or give detailed explanations. Her profile bio said:
"My real name is Cleo, I'm female. I have a medical condition that makes it very difficult for me to engage in conversations or post long answers. I like math and do my best to be useful at this site, although I realize my answers might not be useful for everyone."
Between November 2013 and December 2015, Cleo answered 39 questions on Math.SE about complex math problems involving integration. Her first important contribution was on November 11, 2013, when she solved a difficult integral that had confused other users. The problem stated:
"I need help with this integral:
[…] The approximate numeric value of the integral:
Neither Mathematica nor Maple could find a simple formula for this integral, and searches in WolframAlpha and ISC+ did not return clear formula candidates either. But I still hope there might be a simple formula for it."
Cleo answered the question four and a half hours later with the solution: I = 4 π arccot √φ, where φ is the golden ratio. Her answer included only a link explaining the golden ratio, with no detailed steps.
The Math.SE community questioned if answers without explanations were helpful, as they believed the platform aimed to create useful learning materials. Two days later, Ron Gordon, a patent agent and former physicist, provided a full proof confirming Cleo's solution. His method involved simplifying a complex equation using symmetry and finding the golden ratio in the result. Gordon's detailed work received over 1,000 upvotes on Stack Exchange. He later became known as the "Master of Integration" on the /r/math subreddit. While Cleo's answers were mathematically correct, they caused some disagreement among users for not offering enough educational value.
Cleo's profile on Stack Exchange changed over time. In 2013, her profile included a quote from Srinivasa Ramanujan:
"While asleep, I had an unusual experience. There was a red screen formed by flowing blood, as it were. I was observing it. Suddenly a hand began to write on the screen. I became all attention. That hand wrote a number of elliptic integrals. They stuck to my mind. As soon as I woke up, I committed them to writing."
After this quote, Cleo wrote:
"Remember, you are not locked into a single rule system. You may invent your own, whenever you wish—just use your intuition and imagination."
By the time the account became inactive, her profile had changed to the straightforward statement mentioned earlier.
Investigation
Some people thought Cleo might be a famous mathematician, such as Terence Tao (though Tao said this was not true in an email), Grigori Perelman, Stephen Hawking, or Maryam Mirzakhani. Allison Parshall from Scientific American compared Cleo's work to that of Indian mathematician Srinivasa Ramanujan, who also created complex formulas without explaining them.
In late 2023, a Reddit user named "evilscientist311" studied Cleo's online activity and how Cleo interacted with other accounts on Stack Exchange. This research found several unusual accounts that often communicated with Cleo, including those of Vladimir Reshetnikov and Laila Podlesny. Laila Podlesny had posted a question about a difficult math problem that first made Cleo famous in November 2013. However, "evilscientist311" concluded that Cleo was probably run by a group of friends who worked together on math problems and later stopped using the account after finishing school.
In January 2025, YouTuber Joe McCann made a video about Cleo's identity, using earlier findings from Reddit that showed links between multiple Stack Exchange accounts. McCann said there was not enough proof to know Cleo's true identity for sure. A viewer of McCann's video found a connection between Cleo and other accounts by checking email recovery details. When trying to reset the password for Laila Podlesny's Gmail account, the backup email address matched part of Vladimir Reshetnikov's email. When McCann shared this with Reshetnikov, he confirmed that he was Cleo.
Personal life
The person felt frustrated when they asked questions about integrals on Math.SE because they often got comments such as "Why is this interesting?" or "What makes you think there might be a simple answer?"
Reshetnikov studied theoretical physics at the National University of Uzbekistan in the late 1990s. He worked as a software developer in Tashkent before moving to the United States, where he worked for Microsoft for several years. He is an active contributor to the Mathematics Stack Exchange. On February 8, 2025, Reshetnikov posted a Base64-encoded message on his Stack Exchange profile. When decoded, the message read "Creator of Cleo." Similar encoded messages appeared on other accounts, including those of "Laila Podlesny" and "Oksana Gimmel," showing that these were also accounts created by Reshetnikov. He explained that he created the Cleo persona to create interest in mathematical problems that were not widely discussed on the forum. He said the mysterious character and short answers were meant to help other users learn how to solve problems on their own.