Game-AI Forum

Japanese-style mahjong (Riichi):

• Rules of the European Mahjong Federation: http://mahjong-europe.org/docs/riichi_EN.pdf
• Naoki Mizukami: https://scholar.google.com/citations?us ... AAAJ&hl=en
• Mattari Maajan: http://homepage2.nifty.com/kmo2/
• Mahjong Strategy: http://justanotherjapanesemahjongblog.blogspot.jp/
• tenhou.net, a free online mahjong server with bots: http://tenhou.net/

Chinese-style mahjong:

• Mahjong Competition Rules ("Green Book"): http://mahjong-europe.org/portal/images/docs/mcr_EN.pdf
• Computer Tournament Protocol: http://aigames.nctu.edu.tw/mahjong/protocol.html

Microsoft has produced a very strong AI:
https://medium.com/syncedreview/meet-mi ... b0a63eb871
Very little technical details, unfortunately.