As a wee lad, I learned to play dominoes with the classic western double-six set. As I got older, I learned to play a number of different games with larger sets, most notably the double-twelve set as the usual choice for Mexican Train. Living in Asia for quite some time now, of course I’ve learned a few games witht the Chinese domino set.
The western set can be of any size, usually a double-six set (lightest domino is double-zero and heaviest is double-six) and an upper limit of double-n set. The formula for determining the number of dominoes in a set is ((n^2 + 3n + 2) / 2), where n is the highest doubled number. So, a double-zero set has one domino, a double-one set would has three dominoes, a double-six set has twentyeight dominoes, and a double-eighteen (evidently the largest commercially available set) has one hundred ninety dominoes.
The Chinese set only comes in one variety: double-six. The formula above does not work for that for two reasons: (1) there are no blanks in the Chinese set, and (2) one suit, called the civil suit is duplicated. Thus we have the following 32 dominoes:
- Civil suit has two each of: 6-6, 1-1, 4-4, 1-3, 5-5, 3-3, 2-2, 5-6, 4-6, 1-6, 1-5
- Military suit has one each of: 1-2, 1-4, 2-3, 2-4, 2-5, 2-6, 3-4, 3-5, 3-6 and 4-5
So, how could this set be expanded to a higher double, all the way up to double-eighteen? I figure that the beginning is to determine what are the commanalities for the civil suit tiles? All of the doubles are in that suit, but the non-doubles are: 1-3, 1-5, 1-6, 4-6, 5-6. Why those particular non-doubles? If it’s random, then that means choosing a proportionate number of random tiles from the double-n set. But, I don’t want to just blithely declare it random. Is there some mathematics hidden in the traditional Chinese set’s civil series’ non-doubles and that’s why those are the tiles in that suit in addition to the doubles? Of coursse, the original double-six set’s civil suit’s dominoes must all be in the next higher double-n set’s civil suit and each successive expansion should only add two copies of one domino to the previous expansion’s civil suit.
Is this doable? I’m actually more concerned about the mathematics involved than in playing any games with this super-sized Chinese set, but expanding the rules for known Chinese games with the traditional set is also of some interest. First, I’d like to figure out the expansions.
Gee, I hope all of that’s clear. Let me know if it’s not.