LMI Monthly Test Authors

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Photo of Riad Khanmagomedov

Riad Khanmagomedov


Photo of Ivan Koswara

Ivan Koswara


Photo of Swaroop Guggilam

Swaroop Guggilam


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David McNeill


Photo of Richard Stolk

Richard Stolk


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Rohan Rao


Photo of Rishi Puri

Rishi Puri (purifire)


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Denis Auroux


Photo of Nikola Zivanovic

Nikola Zivanovic


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Prasanna Seshadri


Gabriele Simionato

I didn't know about puzzle games before attending the 1st World Sudoku Championship in 2006. I started solving Sudokus in preparation for the competition, and participated in the Italian championship that year, earning a 3rd place finish. Since then, my life changed a lot: now I own my puzzle company and I enjoy sharing my games to other puzzles enthusiasts. My favorite sudoku variation is Diagonal Sudoku, but I am best known for the introduction of Sudoku & Dragons. About puzzles, I enjoy solving everything that involves loops, especially Yajilin. Also games like Corral and Parking meet my taste. I have developed interest in Maths, and other "nerdy" things, like Rubik's Cube: my personal best is 39''.

Matus Demiger

See below.

Yosuke Imai


Atsumi Hirose


Takeya Saikachi


Daisuke Takei


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Matej Uher

I have started solving logic puzzles since 2008, but first time I took part on WPC Eger in 2011. My most favorite puzzles are loop puzzles, tapa and fillomino. In 2012 I got bronze medal at Slovak Puzzle Championship and joined the Slovak squad to WPC in Croatia. I'm also interested in doing sports, climbing and sleeping. I really hate vegetable and sad mood.

Ko Okamoto (xevs)

27 years old worker for a financial company. Several times participated WPC and 4th was the highest rank (2008, 2011). twitter: @xevs99

No Photo

Gyula Slenker


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Pál Madarassy


Photo of Zoltán Horváth

Zoltán Horváth


Andrey Bogdanov

Few times Russian puzzle champion, participated at World Puzzle Championships. Supports internet site of Russian puzzle club (Diogen). At 2008 was a principal author for puzzles of WPC in Minsk, also has authored two books of puzzles.

Seungjae Kwak (Kwaka)

I started solving puzzles in 2001. That was the first year (and so far, the only year) I participated in the WPC. I started solving Sudokus in 2007. I won the 1st Korea Sudoku Championship but unfortunately, I couldn't participate in the 2nd WSC because I was in the army (another player participated in my place). To make up for this I try to participate in all the on-line competitions including LMI monthly tests. These days I enjoy making sudokus rather than solving puzzles. I want to be not only a good player but also a good author.

Hwangrae Lee (Spica)

I'm a 26 year old graduate student, majoring in mathematics. I started to solve Sudoku from 2010, and now I'm interested in both solving and making variants. My birthday is September 21st, so my sign is Virgo. That's why I'm using my nickname "Spica", which is the alpha star of Virgo.

Grant Fikes (mathgrant)

Grant Fikes is a logic puzzle author in Abilene, Texas whose puzzles have appeared in Sudoku Xtra and in Akil Oyunlari, as well as on his own blog where he has posted hundreds of puzzles. His online persona is an anthropomorphic fox/badger hybrid.

Photo of Palmer Mebane

Palmer Mebane (mellowmelon)

Palmer Mebane's first major competition was the 2010 WPC, which he participated in as a member of the US team that won the competition. On the constructing side, he has posted hundreds of puzzles at his blog Melon's Puzzles.

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Stefan Heine

I am a German puzzle-maker from Hamburg. Since 1995 making puzzles is my main job and I work for about 400 publications around the world - most of them in German speaking countries. I have been to all WSCs since 2006. I developed all sudokus of the US Sudoku Championships in 2009. For the WSC 2010 in Philadelphia, I made some puzzles for the contest and since Hungary 2011, I am the captain of the German sudoku team. In 2005, I organized the national German sudoku championship and have been creating the puzzles for it since then.

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Serkan Yurekli

I have been making puzzles for 5 years and I started to focus on solving in the last 2 years. I am the editor of Akil Oyunlari puzzle magazine and we have published several books including logic puzzles. Inventing Tapa puzzle type and organizing OAPC series are the most valuable works I have done among these.

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Sylvain Caudmont

40 years old french player, I discovered sudoku variants in 2009, around 3 years ago. I was team member of France at WSC Eger in 2011. I also coauthored one sudoku book in 2011 and from time to time I create some sudokus for tests or specialized publications.

Zuzana Hromcová & Matúš Demiger

Zuzana, 16 years old high school student, participated twice at WSC and once at WPC. Few days ago got bronze medal at Slovak Sudoku Championship and joined the Slovak squad to Eger 2011. She likes visual arts, pizza and collecting signatures, contrary sports and skyscrapers puzzles belong to her non-favorite.

Matúš, 18 years old student of journalism, took part at one WSC and three WPC and he also reached the Slovak nomination to Eger, in both championships. His passions are football, menthol sweets and his pencils, however he dislikes classic sudoku and ice-hockey.

Together, they were co-authors of the 5th Sudokucup and many regular Slovak contests. Matúš also constructed sudoku for the 4th WSC in Žilina, puzzles for the 11th 24 HPC and he is the editor of Slovak crossword magazine Lišiak.

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Frédéric Stalder (Fred76)

35 years old, I'm a Swiss trumpet player who got lost in the world of sudoku. I discovered variants in 2009 and it became an obsession for me, so when I don't have my trumpet in my hands, I like playing and creating sudoku ! You can find some of my creations on my blog: Variantes de Sudoku

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Tawan Sunathvanichkul

Tawan Sunathvanichkul is a 19-year old college student from Thailand. He discovered puzzles when he was around seven and started making hand-drawn puzzles since then.
He is the 2011 national crossword puzzle champion and won several sudoku titles in his country. Most of his puzzles were constructed during boring lectures – with him occasionally getting caught.

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Thomas Snyder (motris)

Thomas Snyder is a 2-time World Sudoku Champion and 5-time US Puzzle Champion. He has authored 4 books of puzzles, including the recently released TomTom Puzzles.

Bastien Vial-Jaime (Ours brun)

Obsessed by logic since my very young age, I got caught immediately when I discovered sudoku, from which I entered the world of logic puzzles. Since then, I have been trying to share my time between puzzle solving and organizational activities such as contributing to online and paper competitions, as well as specialized publications. I am also webmaster of ffsudoku.com and I recently co-authored a sudoku book.

Zoltán Gyimesi

I am 34, married and have 3 children. I love to solve logic puzzles and sudoku, but I had to skip a lot of world championships due to my main profession, which is to play chess. I am a professional grandmaster since I am 19, my biggest successes are to be Hungarian champion, Rapid European Champion, and winning silver medal with the Hungarian Team on the Chess Olympiad. I am sure to be the best puzzler among chessplayers, and the best chessplayer among puzzlers :-) I construct puzzles very rarely, they are usually chess related. But those for LMI are exceptions!

László Osvalt

I am László Osvalt, age 40. I am dealing with logic puzzles for 13 years. I was team member of Hungary on several WPC and WSC races since 1999. My favourites are Kakuro and Snake-like puzzles, and the 24 Hours Puzzle Championships. Crossword puzzles are the other large area of my interest.

Károly Kresz

He participated on more WPC in 1990s, his best position was 8th in Brasov (1995) and 11th in Stamford (2000).
He made puzzles for WPC in 1999. And he was the author of the first hungarian logic magazine for many years. He was more times 3rd with team.

Zoltán Németh


Photo of Tom Collyer

Tom Collyer (detuned)

Tom Collyer runs the blog detuned radio, and publishes an original Nikoli-style puzzle every Friday. Away from creating puzzles, he is twice winner of the UK sudoku title, and has participated in three World Sudoku Championships.

Jakub Hrazdira (Gotroch)

Murat Can Tonta

19 years old, Murat is a puzzle designer and enthusiast from Turkey, with a particular liking for loop-based puzzles. His puzzles are regularly published in Turkish logic puzzles magazine Akil Oyunlari and he authored a 24HPC set alongside Serkan Yürekli. He is also an author and judge at the website PuzzlePicnic.

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Geoffroy Hermelin

41 years old, passionate of computer, music, sudoku and other, always ready to participate in the craziest projects.

Laurent Pierre

37 years old, laboratory technician in perfumery, passionate of riddles of all kinds, of trekking and discoveries. Sudoku lover and novice in the creation of puzzles...

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Bram De Laat (para)

I started logic puzzles about 10 years ago after running in an edition of Breinbrekers advertising the Dutch puzzle championship in a bookstore. I instantly noticed I had a knack for these kind of puzzles. I've won one Dutch Puzzle Championship and one Dutch Sudoku championship since then and participated in 5 world championships. Since 4 years I've also been designing puzzles, which can be mostly found on Puzzlepicnic.com and in Breinbrekers.

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David Millar

David Millar is a puzzle author as well as a graphic and web designer, and posts new puzzles at least twice weekly on The Griddle.

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Zafer Hüseyin Ergan

Zafer Hüseyin Ergan is a puzzle enthusiast from Turkiye. He had become a puzzle fan for about ten years. His favourite puzzle types are optimization puzzles and sudokus.

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Chen Cen (cpickerel)

I started to play sudoku 4 years ago and quickly became a dead sudoku fan. I was the twice Chinese Sudoku champion and 7th position of the 5th World Sudoku Championship.

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Jin Ce (jcvb)

I'm 13 years old. I like playing Sudoku, designing puzzles and programming.

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Jan Mrozowski (janoslaw)

Jan Mrozowski is current and double World Sudoku Champion.

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Tejal Phatak

I started solving puzzles in 2007 after the National Sudoku Championship, in which I participated for 'fun'. Having missed to qualify in the Indian team by just a position or two in 2008 and 2009, I finally made it to the team for WPC 2010.

Photo of Amit Sowani

Amit Sowani

I had been introduced to WPC style puzzles and sudoku in 2005, through the national puzzle championships then organized by Hendrik. After participating in a couple of WPCs and one WSC I moved towards the organizing aspect of these competitions since WSC 2008 which we organized in Goa. I hope to see the Indian team do well and stand among the top teams at the world championships. Hoping to return to participating too :)

Mock Test Authors

Several authors contributed to LMI Mock tests.

  • Rajesh Kumar
  • Jakub Ondrousek (jaku111)
  • Branko Ceranic (skywalker)
  • Maruska Benediktova (cauchy)
  • Kshitij Sharma
  • Gaurav Korde
  • Hitesh Gupta
  • Ritesh Gupta

The authors are sorted by order of their tests appeared at LMI (newest test author at the top)