Writing Rules for Bridge - Defining a Bridge Language Back

Writing a set of bidding rules requires a simple language based around the natural language of Bridge. This language must be easily readable and understandable. But, it must also convey the precise meaning of every piece of information influencing a bid. A set of rules written in this language should proceed step by step through a reasoning process identical to a person bidding this system. What should such a language look like? Let's start with the vocabulary.

All of the individual pieces of information necessary for bidding may be thought of as qualities. A hand has qualities such as point count and shape. Each of the suits in the hand has qualities such as the name of the suit and the number of cards in the suit. A person has qualities such as the seat order during a hand. A bid has qualities such as the level of the bid and the suit of the bid.

There are many qualities that the language must define. Each quality must be defined by specifying a word or phrase identifying the quality, what piece of information the quality represents, what values the quality can assume, and how the value of the quality gets set. Notice that the values that a quality can assume may also be a single word or a phrase. So, the vocabulary includes all of the words required to name all of the qualities and their allowable values. This set of words and phrases may be divided into three categories.

First, there are words or phrases that convey a meaning in themselves. For example, the word "shape" refers to a hand being balanced or unbalanced. The phrase "point count" refers to a number representing the strength of a hand as defined by a method of assigning points by card value or suit length. Such phrases may be thought of as simple phrases, since their meaning lies in the phrase itself and does not require determining the meaning of the individual words making up the phrase.

The second category consists of phrases that derive their meaning from the individual words. For example, "my partner's first bid" and "my partner's second bid" are very similar. The difference in meaning being determined by the difference in the ordinal number referring to the bid. The meaning of these type of phrases is determined by an examination of each individual word. Such complex phrases are necessary to describe qualities such as the suit of a bid, where the exact value of the quality depends upon specifying which bid of which player. The language must define a set of words that can be used to build phrases referring to these type of qualities.

Last, the values that qualities can take are also words or phrases. For example, the value of "shape" may be set to either "unbalanced" or "balanced". These are the only two values that "shape" may take. Other values may be numbers. "Point count" may be a number from 0 to 40.

In addition to the words and phrases required to name and give value to all of the qualities, the language requires a few more words. These are words needed to provide structure to the language, to guide the thought process as the qualities and their values are considered. These additional words are more easily explained in the context of the semantics of the language, covered in the following section.

Once a vocabulary is established for the language, the syntax and semantics must be defined. So, let us look at how words, simple phrases, complex phrases and values can be strung together to form a thought process capable of selecting a bid according to a bidding system.

First, what sort of ability is required of the language to simulate a thought process capable of bidding? The language must allow:

	making decisions based upon the value of a quality.
	setting a quality to a specified value.
	inclusion of comments explaining a decision.
	bids to be made.

How does the language provide these four basic abilities? By specifying the syntax of four types of rules.

1. If rules

   If left side comparison right side
   

   The syntax of the "If" rule is the word If, followed by a reference to some quality, followed by the type of comparison to perform, followed by either a reference to another quality or a specific value to be tested against. To execute the rule, the game determines the current value of the quality and tests it, as specified, against the provided value. The result of the test will be either true or false. The result of the test is then used to determine which rule the game will execute next.

   Which rule is executed after an "If" rule, is determined by the indentation of the rules. That is, an "If" rule may have other rules indented beneath it. These rules belong to the "If" rule. These rules will only be executed when the parent "If" rule evaluates to true. When the "If" rule evaluates to false, the child rules will be skipped. Execution will proceed to the next rule that is at the same indentation level or less than the "If" rule.

   In the following example, when rule 1 is evaluated and found to be true, the next rule executed would be rule 2. When rule 1 is evaluated and found to be false, the next rule executed would be rule 3.

   If rule 1   If rule 2 If rule 3

   The "If" rule is the only rule that affects the game's order of execution. All other rules are simply executed and the game proceeds to the next rule.

   Note that the right side of the "If" rule can be a reference to either another quality or to a specific value. Obviously, if the right side is a specific value, the value must be one of the values allowed for the quality on the left side. If the right side is a reference to another quality, the allowable values for the quality on the right side must be the same as the allowable values for the quality on the left side. Both sides are evaluated to determine their current value and their current values are tested according to the comparison.

   Some examples of "If" rules: If shape is balanced If point count <= 11 If length of my first bid suit >= 6 If If length of Hearts = 4

2. Set rules

   Set quality to value
   

   The syntax of the "Set" rule is the word Set, followed by a reference to some quality, followed by the word to, followed by the value to set the quality. When the game executes a "Set" rule, the value of the quality is set to the value specified.

   Some examples of "Set" rules: Set best suit to suit not selected Set my partner's first bid to one in a suit Set partner's point count min to 12 Set partner's point count max to 21

3. Comment rules

   Comment: text
   

   The syntax of the "Comment" rule is the word Comment:, followed by the text of the comment. When the game executes a "Comment:" rule, the text is stored for review by the user.

   Some examples of "Comment:" rules: Comment: My partner opened the bidding with 1 in-a-suit Comment: Partner has 12-21 points Comment: With 19+ points jump bid a new suit Comment: With 7 points or less and no 5+ card suit, pass

4. Bid rules

   Bid quality
   

   The syntax of the "Bid" rule is the word Bid, followed by a quality representing a bid. When the game executes a "Bid" rule, the quality is evaluated to determine the bid to be made.

   Some examples of "Bid" rules: Bid 1 Spade Bid 1 of best suit Bid 2 of my first bid suit Bid 2 of my partner's first bid suit

Now let's examine the semantics of the language, that is, how qualities and values can be constructed in such a way that they convey a common meaning. As explained above on this page, there are qualities that can be expressed using a word or a simple phrase and there are qualities that require a complex phrase to be expressed. There are also values of the qualities. Also, as seen from the definition of the "If" rule, there are comparisons. Please continue now to one of these pages for additional explanation of how qualities and values are expressed in the language.