Writing Rules for Bridge - Background Back

The first objective of this game is to provide a means to both document and test a set of bidding rules. To document a set of bidding rules means to formulate a small, simple language in which to write the rules for any bidding system. A language so easily understandable that anyone can learn the bidding system by reading the rules. But, though simple, the language must be capable of expressing the entire bidding system. The language should capture the system so completely that a computer could use those rules to derive bids for any conceivable hand. The proof comes when the program uses those rules to bid a test group of hands and bids every hand correctly, according to the system.

This game meets that objective by defining a simple language based around the natural language of Bridge. For instance, suppose your partner opened a hand with 1 NoTrump. Now, it is your first turn to bid. The language might reflect this situation in the rules:
 

If my partner's first bid is one notrump
   1: If point count <= 7
      a: If shape is balanced Pass
      b: If length of longest suit >= 5 and longest suit is not
         Clubs bid 2 of longest suit
      otherwise: Pass
   2: If point count >= 8 and point count <= 9
      a: If shape is balanced bid 2 NoTrump
      b: If longest suit is a major suit and length of longest suit
         >= 6 bid 4 of longest suit
      otherwise: Bid 2 NoTrump
   3: If point count >= 10 and point count <= 14
      a: If shape is balanced bid 3 NoTrump
      b: If length of longest suit >= 6 and longest suit is a major
         suit bid 4 of longest suit
      c: If length of longest suit >= 5 and longest suit is not
         Clubs bid 3 of longest suit
      otherwise: Bid 3 NoTrump
   4: If point count >= 15 and best suit is any suit bid 3 of best
      suit

The details of the language, the vocabulary, the syntax and the semantics, are covered in Writing Rules for Bridge - Defining a Bridge Language. Before looking at the language itself, however, let's first consider some reasons for defining this language.

Two of the best ways of learning and understanding the art of bidding are by reading books and by studying bidding sheets. But, as good as these sources are, I still find myself sometimes wanting another method for describing a bidding system. I want something that packs all of the information contained in a book into a condensed form more like a bidding sheet. To me, this simple language makes it possible to write rules that are both economical and complete. Rules that can be easily read to be thoroughly understood.

Once you have the rules written in this language, it becomes easy to alter rules or even move rules around. Changing the point count for bids of particular ranges becomes simple. Having the rules written opens other possibilities, too. A sequence of increasingly complex systems could be written to ease beginning Bridge players along toward full understanding of a complete bidding system. Or, two sets of bidding systems could be matched against each other to determine which set bids better.

To be useful, the language needs a way for a person to write a set of rules without having to memorize the language itself. In other words, the language needs an editor that actively assists in the writing. The editor knows the language and helps you translate your thought processes into rules. This game has just such an editor which you can read about in Editing the Rules.

The language also requires some means to trace the rules as they are being evaluated during any particular player's turn. That is, it is necessary to watch as each rule is applied and to see the results of that rule. This is necessary for two reasons. One, a person writing a set of rules may make a mistake which causes an incorrect bid to be made in some bidding situation. The writer must be able to reproduce the situation and watch as each rule is executed by the computer in order to determine the exact line causing the error. And, two, a person studying the system may want to watch the decision making process for some bid to better understand the reasoning behind the bid. To satisfy this requirement, the game allows the user to trace the execution of the rules during any player's turn. For more information, please refer to Tracing the Rules.