Duplicate mahjong

Assessment

Confidence

documented a published ruleset or rule description exists and is cited

Evidence

corroborated two or more independent sources agree on the facts that define this variant

Cross-comparison

What each source was read to say, set side by side. The numbers are the sources above.

• [1] a form of play similar to usual international competition forms; the walls are prebuilt so as to remove the element of luck, making winning a matter of skill; designed so mahjong can be considered a mind sport and qualify as a potential Olympic event
• [2] the Mahjong International League's own rules page, fetched and confirmed to exist at the cited URL
• [3] MIL describes itself as operating under the International Mind Sports Association with member associations in more than 50 countries, states that it initiated the duplicate format to decrease luck, and calls it an innovation that sublimates mahjong from a game into a real mind sport. It recognises MCR, Riichi and Sichuan rules as the three main international competition rulesets
• [4] the rules, read at the live page: 'different players play the same hand under the same conditions, and compare their points'. It uses 136 tiles and 'the 8 flower tiles will be banned'. Tile backs carry serial numbers. At each hand, staff restore each player's 34 tiles, '21 wall tiles placed in sequence and 13 initial hand tiles', so 'Walls building and dice rolling are not needed'. Each player draws only from his own wall, and a kong replacement comes from that wall in sequence. Tables do not play the same hand at the same time, so sessions need not start from the East round. Calling out a win or a score is prohibited, and a player shows the winning tile instead
• [4] THE BASE RULESET AND THE SCORING: the page is titled 'Gameplay under Duplicate Format of MCR'. Individual play compares each player's points with 'the average point of the same hand played by all players', converted into IMP. Teams total their points per hand and convert them to IMP over 16 hands. This is duplicate bridge's comparison scoring applied to MCR hands
• [5] the organisation behind it: MIL was founded in 2015, with an establishment ceremony at the Diaoyutai State Guest Hotel, Beijing, on 11 May 2015. It is registered in Lausanne, held the 1st World Mahjong Sports Games in Sanya on 24-28 October 2015, and was recognised as an IMSA observer on 26 February 2016. 'As of 5 April 2017 Mahjong is the sixth official game to be played at IMSA Elite Games'

Reading it

The rules are now read at the source, not only confirmed to exist, and they change what the node is. MIL's current page defines duplicate play as the 'Duplicate Format of MCR'. It is the MCR ruleset played with 136 tiles and no flowers, pre-arranged and serial-numbered walls, and bridge-style IMP scoring against the average score on the same deal. So it is a competition format for an existing ruleset, not an invention outside the mahjong line. By descent it belongs beside MCR, and the chart's placement under 'modern inventions (not descendants)' is best read as 'a modern invention in how the game is contested'. The chart's parent link is fixed, so this is recorded here rather than redrawn. MIL itself dates from 2015 and has been an IMSA observer since 2016.