At the end of 2013, a new user appeared on the Stack Exchange's mathematics forum under the pseudonym Cleo. Later, details were added to her profile information that she was a female user. For two years, he answered complex mathematical questions correctly, without explaining how the solution arose, after which he disappeared. By this time, Cleo had already become a legend among forum users.

  User identity revealed in 2025

  Forum participants tried to find out who was hiding behind this profile for more than ten years. Only at the beginning of 2025 did it become known that the account was created by a programmer from Uzbekistan, Vladimir Reshetnikov, who lives in the USA. The "Meduza" publication published an article explaining why the mysterious Cleo interested mathematicians so much and how the true owner of the calculation was found. The article was translated by Gazeta.uz.

  The genius mathematician Kleo, whose identity users have been trying to identify for more than a decade, turned out to be from Uzbekistan.

  Cleo's unexplained responses:

•   On November 11, 2013, one of the participants of the Stack Exchange mathematics forum asked for help in solving an integral equation. After four and a half hours, he received the correct answer from a user with the pseudonym Cleo. However, the author of the response did not explain how this solution came about, and did not leave any additional comments at all.
•   This was Cleo's second response to the forum and remains the most popular to this day. He announced the first one a few days ago, but it took more time - almost 19 hours - to find the solution. Other forum participants became interested in the mysterious mathematician and decided to test his profile. It contained two quotes from Gauss (the great German mathematician Karl Friedrich Gauss) and Ramanujan (the Indian mathematician Srinivasa Ramanujan), as well as another phrase: "Remember, you are not limited to a single system of axioms. You can come up with your own at any time - just use your intuition and imagination."

  Cleo's first self-reflection

  At the end of 2014, a Bitcoin wallet address appeared in the profile description, through which it was possible to "express gratitude" to Cleo for his answers. At the beginning of 2015, the data was updated again and has not changed since:

"My real name is Cleo, I'm a woman. I have a disease that makes it difficult for me to participate in discussions or write long answers, for which I apologize. I love mathematics, and on this site, understanding that my answers may not be useful to everyone, I will do everything possible to be useful."

39 responses in two years

  In just two years, Cleo published 39 answers to complex mathematical problems, the last one being on December 31, 2015. They were all given correctly and quickly, but without any details explaining how the user solved the problems. In some cases, the correctness of the answer was proven by other members of the community.

  Some forum participants disliked Cleo's response style. What irritated the users was that they received a ready-made answer, but they didn't understand how the author of the comment managed to achieve this solution. This contradicted the main purpose of the site - the exchange of knowledge with a team of like-minded people. Some didn't consider the anonymous user's comments without detailed explanations and calculations as a complete answer.

Forum Legend

  In these two years, Cleo became a legend in the forum, and his image began to be enriched with additional details. For example, there were rumors that he was only 15 years old, although this was not indicated on his profile. Forum users, however, did not have other reliable sources of information (such as social media pages). For a long time, members of the community tried to find out who was hiding behind Kleo's profile. Sometimes there were even people who claimed that the secret account belonged to them. However, this information was not confirmed.

ssumptions for CleoA

  The hosts of the Science Quickly podcast, published on the website of the Scientific American publication, recalled the most interesting theories put forward by users in 2023. For example, community members speculated that Maryam Mirzakhani of Iran (who died in 2017 at the age of 40) might be hiding behind the name Cleo. She was the first woman to win the Fields Award, the most prestigious award in mathematics.

  Others believed that Terence Tao, an Australian and American mathematician and professor at the University of California, Los Angeles, would answer these questions. The podcast hosts even contacted him for comment, but he denied these rumors. Also, some supercomputer might be providing solutions however, at that time (and still today), the capabilities of computer programs to solve such complex integrals were very limited.

The most incredible guess

   The most incredible version was related to Stephen Hawking. The famous British theoretical physicist died in 2018, much after Cleo's disappearance. Some users speculated that the scientist might have enjoyed himself this way. Moreover, the mysterious disease mentioned in the profile also corresponded to this theory.

His identity went beyond the scope of the forum.

   There was a time when attempts to determine who Cleo was went beyond the scope of the mathematical forum. In one of the Reddit studies, it was stated that the information about the disease was not true. Most of Cleo's comments have now been deleted. However, according to indirect testimony from forum participants, he once explained his unwillingness to comment on the answers not due to illness, but for religious reasons, and called himself the "Namagiri priest." This goddess was worshipped by the mathematician Srinivasa Ramanujan, whom she quoted in her profile.

Cleo - a whole team

   In another study, a user with the pseudonym evilscientist311 attempted to track Cleo's activity periods and compile a list of other accounts he was in contact with. She identified several accounts that stood out in the common background, including profiles named Vladimir Reshetnikov and Laila Podlesny. From the final score, including after his answer, a question was asked that drew attention to Cleo. However, the user who conducted the study did not attribute the authorship of the Cleo account to a specific person and concluded that it was a product of collective creativity:

   "Personally, I think a group of friends I met at university decided to create a Cleo account. In it, one person answered problems published by other accounts (of course, they were solved in advance). They created the calculation in the middle of their studies at the Faculty of Mathematics and continued to use it until graduation. After that, they found work and went their own way, so the Cleo account was never used again."

Joe McKenn's research video

   In general, the author of the study was on the right track, but did not draw a very accurate conclusion. As can be seen, Cleo's account still belonged to one person. At the end of January, blogger Joe McKenn prepared a video based on this study. He also noticed strange situations during periods when some forum users were active, but believed that the data was insufficient to draw clear conclusions.

   But this video prompted one of the viewers to check if there was any connection between Cleo and the most frequently interacting users. Leila Podlesny's profile showed a Gmail address. The user attempted to log in to this account, then allegedly asked to restore the forgotten password. This allowed him to see several first letters of the backup email address, which turned out to be identical to the email address indicated in Vladimir Reshetnikov's profile.

Direct appeal to Reshetnikov

   Joe McCann spoke about all this in his second video, which was released on February 17. The blogger stated that he directly contacted Reshetnikov, and he was forced to confirm that the accounts of Kleo and Leila, as well as two other accounts, belonged to him.

   By the way, Cleot's identity was revealed a little earlier, on February 8th. Apparently, Vladimir Reshetnikov decided not to wait for the release of the video, and after McCann approached him for comment, he posted a coded message in Base64 format on his Stack Exchange profile. Reddit users deciphered it and found that it contained the phrase "Creator of Cleo." Another coded message appeared on the profiles of Leila Podlesny and Oksana Gimmel: "Kleo's alter ego, created by Vladimir Reshetnikov."

He is a graduate of the National University of Uzbekistan

    Reshetnikov himself confirmed his involvement in the creation of Cleos with the phrase "mea culpa" (translated from Latin as "my fault") on the social network X, and also revealed some details in his responses to other messages. In particular, he said that he did not plan to disclose the truth, but was forced to do so after Joe McCann presented him with evidence. His current workplace is not indicated, but in the past, he worked at Microsoft Corporation at different times (more than eight years in total). Including during the period when Cleo's profile was active.

Was the mysterious woman more interesting to users?

   Reshetnikov explained his decision to create the image of a mysterious female mathematician by the fact that his questions and mathematical problems, which he proposed to discuss, did not attract the attention of the forum participants. McCann said that Cleo's messages actually motivated other users: an annotated response prompted them to solve one or another integral. At the same time, the blogger noted that Reshetnikov did not always believe in the correctness of these answers.

   Although users uncovered a ten-year-old secret and became convinced that no genius Cleo actually existed, this apparently didn't upset them much. Perhaps most of them liked the image of a mysterious woman who easily solved the most complex integrals.

"The very idea of Cleo is important, not whether it actually exists or not... just like Jesus," wrote one user.

According to Vladimir Reshetnikov, he is 45 years old. His LinkedIn profile, linked to his GitHub account, shows that he studied theoretical physics at the National University of Uzbekistan in the late nineties. Reshetnikov worked for several years as a software developer in Tashkent, after which he moved first to Russia, and then to the USA.

   His current workplace is not indicated, but in the past, he worked at Microsoft Corporation at different times (more than eight years in total). Including during the period when Cleo's profile was active.

Was the mysterious woman more interesting to users?

   Reshetnikov explained his decision to create the image of a mysterious female mathematician by the fact that his questions and mathematical problems, which he proposed to discuss, did not attract the attention of the forum participants. McCann said that Cleo's messages actually motivated other users: an annotated response prompted them to solve one or another integral. At the same time, the blogger noted that Reshetnikov did not always believe in the correctness of these answers.

  Although users uncovered a ten-year-old secret and became convinced that no genius Cleo actually existed, this apparently didn't upset them much. Perhaps most of them liked the image of a mysterious woman who easily solved the most complex integrals.

   "The very idea of Cleo is important, not whether it actually exists or not... just like Jesus," wrote one user.