https://cotuongne.com/blog Xiangqi, fog variants, and engine work from Mistboard. en https://cotuongne.com/blog/banqi-chariot-endgame mistboard:blog:banqi-chariot-endgame Fri, 30 Oct 2026 12:00:00 GMT A Mistboard player told us our 40-move draw rule was too short for the endings where three pieces beat two. We solved one: a chariot, horse and soldier beat a chariot and horse in 67 moves, and nothing is captured in the first 43. Banqi on Mistboard now draws at 60 moves. The win is in a study, move by move, with the tablebase beside the board. https://cotuongne.com/blog/unstyled-first-paint mistboard:blog:unstyled-first-paint Fri, 23 Oct 2026 12:00:00 GMT The rules pages and the players pages both showed as bare text for a moment before snapping into their design. The causes were different, and the check written for the first passed the second. https://cotuongne.com/blog/helpmates-in-xiangqi mistboard:blog:helpmates-in-xiangqi Tue, 20 Oct 2026 12:00:00 GMT In a helpmate both sides cooperate so Red can mate. A search found 164 helpmates in two for xiangqi; try the best ten, solutions hidden until you ask. https://cotuongne.com/blog/general-blunder-challenge mistboard:blog:general-blunder-challenge Mon, 19 Oct 2026 12:00:00 GMT General Blunder is a xiangqi bot that plays its worst move every turn, so beating it is easy. Two challenges for anyone who wants more: get a draw, then make it win. https://cotuongne.com/blog/zuo-wenjing mistboard:blog:zuo-wenjing Fri, 16 Oct 2026 12:00:00 GMT The 2022 women's world champion and a double gold medallist at the 2023 Asian Games. Her title run in Kuching and her 2026 season, five games on the board, 32 games analysed. https://cotuongne.com/blog/fortress-and-atomic-xiangqi-on-hold mistboard:blog:fortress-and-atomic-xiangqi-on-hold Tue, 13 Oct 2026 12:00:00 GMT On 11 October we stopped new games of Fortress Xiangqi and Atomic Xiangqi so we can redesign them. In Fortress the drops took over a small board; Atomic only stopped looping after the cannon got its own exception. Finished games still replay. https://cotuongne.com/blog/banqi-perpetual-chase mistboard:blog:banqi-perpetual-chase Mon, 12 Oct 2026 12:00:00 GMT In banqi a chased piece often has one safe square, so a chase can go back and forth until the position repeats, and under plain threefold repetition the chaser alone decides the draw. Tournament rules allow it and apps cap the chase at 7 or 10 moves. Mistboard forbids the chase move that would repeat a position a third time, and leaves chases that go somewhere alone. https://cotuongne.com/blog/jieqi-puzzle-search mistboard:blog:jieqi-puzzle-search Sun, 11 Oct 2026 12:00:00 GMT We searched 2,939 positions from 50 jieqi games for puzzles. 58 had one clearly best move and 15 of those turned on a hidden piece. None of the 15 passed the rules our xiangqi puzzles go through, and we stopped looking. https://cotuongne.com/blog/longest-forced-mates-xiangqi mistboard:blog:longest-forced-mates-xiangqi Fri, 09 Oct 2026 12:00:00 GMT A horse and a soldier beat a general with both advisors and both elephants, and the slowest win in that endgame takes 65 moves. Seven records from xiangqi endgame tablebases, with the lines, and five of them end with the loser having no legal move. https://cotuongne.com/blog/xiangqi-endgames mistboard:blog:xiangqi-endgames Thu, 08 Oct 2026 12:00:00 GMT Xiangqi basic endgames, which win and which draw: a table of 35 common endings with the result and the key idea for each, every result checked against the chessdb.cn tablebase, and every position ready to practice against the computer. https://cotuongne.com/blog/benedict-xiangqi mistboard:blog:benedict-xiangqi Thu, 08 Oct 2026 12:00:00 GMT We put Benedict Chess’s rule on the xiangqi board: nothing is captured, and every enemy piece your moved piece attacks joins you. The game has no endgame and no draws, and the first mover wins 78% of engine games, nearly all of it from one cannon move. The pie rule looks like the repair. https://cotuongne.com/blog/duck-xiangqi-game-tree mistboard:blog:duck-xiangqi-game-tree Wed, 07 Oct 2026 12:00:00 GMT Red’s first Duck Xiangqi turn reaches more positions than a full xiangqi move by each side. About half of them leave the opponent exactly the same choices, so a search can skip them. What is left still cuts how far an engine sees almost in half. https://cotuongne.com/blog/chariot-cannon-repetition-key mistboard:blog:chariot-cannon-repetition-key Wed, 07 Oct 2026 12:00:00 GMT A one-character bug in Mistboard's xiangqi repetition key let a game end in a threefold draw after a position had occurred only twice. https://cotuongne.com/blog/solver-audit mistboard:blog:solver-audit Tue, 06 Oct 2026 12:00:00 GMT We ran an exhaustive solver over every short continuous-check composition in 適情雅趣 (1570), 渊深海阔 (1808) and a modern collection: 172 problems, asking whether the printed solution is the only one. Forty-five are. Seventy have a second winning continuation somewhere in the tree, fourteen have a second first move, nine can be mated faster, and three records turned out to be corrupt: the position as recorded cannot be the one the composer meant. https://cotuongne.com/blog/pikafish-reveal-bug mistboard:blog:pikafish-reveal-bug Sat, 03 Oct 2026 12:00:00 GMT Our Pikafish jieqi bot rated some reveals far better than they were. Two bugs caused it. Both are fixed, at little or no cost in strength. https://cotuongne.com/blog/katago-jungle mistboard:blog:katago-jungle Sat, 03 Oct 2026 12:00:00 GMT A Jungle Chess engine that learned by playing itself now sits above Misty. In 200 games against Misty it won 82, lost none and drew 118. https://cotuongne.com/blog/tony-fung-ga-zen mistboard:blog:tony-fung-ga-zen Sat, 03 Oct 2026 12:00:00 GMT Hong Kong's first Asian individual champion and its 2022 world championship finalist. His last fifteen months and the 2022 run, six games on the board, 50 games analysed. https://cotuongne.com/blog/ab-jchess mistboard:blog:ab-jchess Fri, 02 Oct 2026 12:00:00 GMT AB-JChess, an open-source jieqi engine with its own neural network, now sits above Pikafish Level 8 on Mistboard. It beat full-strength Pikafish 248 to 136 in 400 games. https://cotuongne.com/blog/lai-ly-huynh mistboard:blog:lai-ly-huynh Fri, 02 Oct 2026 12:00:00 GMT The first world champion from outside China, unbeaten in Shanghai and winner of the final with black. His title run and the year since, five wins on the board, 38 games analysed. https://cotuongne.com/blog/lai-ly-huynh-co-tuong mistboard:blog:lai-ly-huynh-co-tuong Fri, 02 Oct 2026 12:00:00 GMT Nhà vô địch cờ tướng thế giới đầu tiên không đến từ Trung Quốc, bất bại ở Thượng Hải và thắng trận chung kết khi cầm quân Đen. Hành trình lên ngôi và một năm sau đó, năm ván thắng trên bàn cờ, 38 ván được phân tích. https://cotuongne.com/blog/jieqi-bot-wins mistboard:blog:jieqi-bot-wins Thu, 01 Oct 2026 12:00:00 GMT Since August 23, people have played our jieqi bot 596 times and beaten it 14 times. Here is how those games were won, and seven new levels for everyone else. https://cotuongne.com/blog/one-thousand-games mistboard:blog:one-thousand-games Wed, 30 Sep 2026 12:00:00 GMT Since June 1, people have finished 1,000 games on Mistboard, most of them in September. Thank you for playing. https://cotuongne.com/blog/cao-yanlei mistboard:blog:cao-yanlei Fri, 25 Sep 2026 12:00:00 GMT Beat the world champion 12 to 8 in a ten-game match in January, then the rest of his season through the first stage of China's top league. Six games on the board, all 75 analysed. https://cotuongne.com/blog/banqi-statistics mistboard:blog:banqi-statistics Wed, 23 Sep 2026 12:00:00 GMT MistyBanqi played itself 200 times at ten million nodes a move under the Taiwanese competition rules. On the engine’s own point scale, a lead under ten points is a coin flip at every stage of the game, and the side that loses its general first loses 87% of the time. https://cotuongne.com/blog/pikafish mistboard:blog:pikafish Tue, 22 Sep 2026 12:00:00 GMT Play Pikafish, the open-source xiangqi engine built from Stockfish, in your browser. Free, no account, no download. Choose a level, play it at jieqi, and review your games with it. https://cotuongne.com/blog/choi-co-tuong-voi-may mistboard:blog:choi-co-tuong-voi-may Tue, 22 Sep 2026 12:00:00 GMT Chơi cờ tướng với máy ngay trên trình duyệt, đối thủ là Pikafish, engine cờ tướng mã nguồn mở phát triển từ Stockfish. Miễn phí, không cần tài khoản, không cần tải về. Chọn cấp độ, chơi cờ úp, và xem lại ván đấu bằng engine. https://cotuongne.com/blog/most-played-move mistboard:blog:most-played-move Mon, 21 Sep 2026 12:00:00 GMT In 144 of 4,121 common opening positions, the move club players choose most often loses winning chances against the engine at twenty million nodes. Ten of them, with what the masters played in each era, and a study holding all 144. https://cotuongne.com/blog/yin-sheng mistboard:blog:yin-sheng Mon, 21 Sep 2026 12:00:00 GMT 31 games without a loss across the league qualifier, the Shanghai Cup and the first league stage, August to September 2026. How he plays, five games on the board, all 31 analysed. https://cotuongne.com/blog/lichess-analysis-accuracy mistboard:blog:lichess-analysis-accuracy Sun, 20 Sep 2026 12:00:00 GMT Lichess analyses each move at a million nodes, about a second of one core. I re-ran 300 games at twenty times that to see what the budget trades away: the blunders hold, the inaccuracies move. https://cotuongne.com/blog/horde-xiangqi mistboard:blog:horde-xiangqi Tue, 15 Sep 2026 12:00:00 GMT We put Horde on the xiangqi board and measured it before building anything: twelve start arrays, two soldier rules, each played four times by an engine against itself. With xiangqi’s own soldier the army wins every game by one trick; give the soldier the crossed move from the start and the game becomes a siege that draws three times in four. We are publishing the measurement, not the variant. https://cotuongne.com/blog/anti-xiangqi mistboard:blog:anti-xiangqi Sun, 13 Sep 2026 12:00:00 GMT We put antichess on the xiangqi board and measured it before designing anything. Black has two moves to find in the opening, Red cannot go wrong, and then the palace keeps five pieces a side out of reach. Every other opening loses, 63 of them provably. We are publishing the measurement, not the variant. https://cotuongne.com/blog/en-passant-under-fog mistboard:blog:en-passant-under-fog Sat, 12 Sep 2026 12:00:00 GMT My fog of war chess engine recorded the en passant square under standard chess legality, in a variant with no such rule. En passant availability decides what a pawn can see, so the true board fell out of the engine's belief and it finished the game against 41 worlds that did not exist. https://cotuongne.com/blog/duck-xiangqi-strategy mistboard:blog:duck-xiangqi-strategy Fri, 11 Sep 2026 12:00:00 GMT Chinese chess with one duck both players share. The rules take a minute to read. What decides your first game takes longer, starting with the fact that the duck you place is a cannon platform for your opponent and never for you. https://cotuongne.com/blog/puzzles-with-more-than-one-solution mistboard:blog:puzzles-with-more-than-one-solution Fri, 11 Sep 2026 12:00:00 GMT A solver found a real mate and was told to try again. 382 served puzzles could do that. How the miner admitted them, the patch that half-fixed it, the rule lichess uses instead, and what came out of the corpus. https://cotuongne.com/blog/jieqi-openings mistboard:blog:jieqi-openings Fri, 04 Sep 2026 12:00:00 GMT Jieqi has no opening book. It has an argument about the first move, running on Chinese forums among players with thousands of games, never written down in English. Why a face-down piece is a one-shot option you can waste, five openings ranked, and the pawn push weighed against the crossed cannon on all six reveals. https://cotuongne.com/blog/khai-cuoc-co-up mistboard:blog:khai-cuoc-co-up Fri, 04 Sep 2026 12:00:00 GMT Cờ úp không có sách khai cuộc. Nó chỉ có một cuộc tranh luận về nước đi đầu tiên, chạy nhiều năm trên các diễn đàn Trung Quốc giữa những người chơi hàng nghìn ván, chưa từng được viết ra bằng tiếng Anh hay tiếng Việt. Vì sao một quân úp là quyền chọn dùng đúng một lần mà bạn có thể phí đi, năm khai cuộc được xếp hạng, và thế tiến tốt đặt lên bàn cân với pháo qua sông trên cả sáu khả năng lật. https://cotuongne.com/blog/jieqi-platform mistboard:blog:jieqi-platform Thu, 03 Sep 2026 12:00:00 GMT Play jieqi against the engine or a friend, free and without an account, then review the game with analysis that separates your choices from your luck. https://cotuongne.com/blog/co-up mistboard:blog:co-up Thu, 03 Sep 2026 12:00:00 GMT Chơi cờ úp với máy hoặc với bạn bè, miễn phí và không cần tài khoản, rồi xem lại ván đấu với phân tích tách riêng phần bạn chọn khỏi phần bạn lật trúng. https://cotuongne.com/blog/luat-co-up mistboard:blog:luat-co-up Thu, 03 Sep 2026 12:00:00 GMT Luật cờ úp đầy đủ: cách bày quân, cách đi quân úp trước và sau khi lật, ăn quân úp, chiếu bí và các trường hợp hòa. https://cotuongne.com/blog/how-puzzle-mining-works mistboard:blog:how-puzzle-mining-works Wed, 02 Sep 2026 12:00:00 GMT A miner that reads real xiangqi games, finds the moves people got wrong, and keeps the positions where exactly one move wins. About one blunder in nine survives it. Here is the algorithm, the code, and some of what it kept and threw away. https://cotuongne.com/blog/xiangqi-match-fixing mistboard:blog:xiangqi-match-fixing Mon, 31 Aug 2026 12:00:00 GMT Between 2024 and 2026 the Chinese Xiangqi Association sanctioned 49 people for buying and selling games, and a Hangzhou court convicted six grandmasters of bribery. What happened, why it paid, who ruled, and what is still unproven. https://cotuongne.com/blog/jungle-den-term mistboard:blog:jungle-den-term Mon, 31 Aug 2026 12:00:00 GMT Misty, our Jungle Chess engine, has no idea of a den race. Three ways to teach it one came back null or negative: races decide 4.7% of games at full strength, and a 12 times deeper search sees the loss a median of one ply sooner. https://cotuongne.com/blog/xiangqi-world-championship mistboard:blog:xiangqi-world-championship Sun, 30 Aug 2026 12:00:00 GMT Every winner of the Xiangqi World Championship since 1990, why the Chinese national title is the harder one, and how a Vietnamese player took it out of China for the first time in 2025. https://cotuongne.com/blog/xiangqi-champions mistboard:blog:xiangqi-champions Sat, 29 Aug 2026 12:00:00 GMT Every winner of the Chinese national xiangqi championship since 1956, and an annotated game for thirteen of them. Plus the nine hundred years before the title existed, and the decade that has been struck from the record. https://cotuongne.com/blog/titled-players mistboard:blog:titled-players Thu, 27 Aug 2026 12:00:00 GMT Verified titled players get a gold badge beside their name, a coaching page students can find, and a front page that will carry their work. Verification takes about two minutes. https://cotuongne.com/blog/riverbank-cannon mistboard:blog:riverbank-cannon Sun, 23 Aug 2026 12:00:00 GMT Red’s opening cannon reaches the riverbank first, one move from firing down any of five files, and in fog you never see it coming. Whether that breaks the game came down to one elephant move, one poisoned defense, and a coin flip we priced with the engine. https://cotuongne.com/blog/skill-vs-luck mistboard:blog:skill-vs-luck Sat, 22 Aug 2026 12:00:00 GMT Half the moves in banqi, jieqi, and flip jungle are dice rolls, so a chess-style review blames you for variance. Mistboard’s game review splits every flip into the decision and the tile: luck-stripped accuracy, a luck line on the advantage graph, and what 52 human-versus-engine games say about who really earned their wins. https://cotuongne.com/blog/flip-jungle-skill-ceiling mistboard:blog:flip-jungle-skill-ceiling Thu, 02 Jul 2026 12:00:00 GMT Flip Jungle is 4×4 Jungle Chess with every animal face-down. A near-perfect engine shows how much skill survives the flips: 512 times the search buys about 242 Elo and still loses 23% of its games. https://cotuongne.com/blog/dou-shou-qi-engine mistboard:blog:dou-shou-qi-engine Sat, 27 Jun 2026 12:00:00 GMT Building an engine for Jungle, also called Animal Chess: alpha-beta search and a hand-written evaluation went 11-2 with 187 draws against the strongest open-source engine I could run. A learned evaluation and a tablebase didn't help. https://cotuongne.com/blog/misty mistboard:blog:misty Sun, 21 Jun 2026 12:00:00 GMT Misty is Mistboard's Fog of War chess engine: how it sees, searches possible boards, avoids hidden catastrophes, and where the current version stands. https://cotuongne.com/blog/mistybanqi mistboard:blog:mistybanqi Sat, 20 Jun 2026 12:00:00 GMT MistyBanqi is the engine you play in banqi on Mistboard: a classical search engine with a hand-written evaluation. How it thinks, and the blind spot worth knowing: it can draw a game it has already won. https://cotuongne.com/blog/server-enforced-fog mistboard:blog:server-enforced-fog Mon, 08 Jun 2026 12:00:00 GMT How Mistboard keeps hidden information on the server: canonical state, seat-scoped views, private live rooms, and public postgame review. https://cotuongne.com/blog/chess960-starting-positions mistboard:blog:chess960-starting-positions Thu, 07 May 2026 12:00:00 GMT Stockfish 18 rankings for all 960 Chess960/Fischer Random starting positions. Most balanced: SP-418 and SP-563; standard chess is near median.