This section illustrates how to use patterns when creating topic rules.
Example 1
The simplest pattern consists of a sequence of terms, such as bank loan fee. The default interpretation of this pattern is that the terms may occur in any order, but they must be next to each other. This essentially forms a Boolean AND expression. Since the adjacency constraint is pairwise between terms, this pattern is interpreted as:
((bank AND loan WITHIN 1) AND (loan AND fee WITHIN 1))
Example 2
The adjacency constraint can be increased or eliminated by placing a dot operator (.) and a number in between the terms. Following the dot operator with an asterisk (.*) eliminates the adjacency constraint. For example, the pattern bank .3 loan .* fee is interpreted as the Boolean expression:
((bank AND loan WITHIN 3) AND (loan AND fee))
Example 3
To enforce order between two terms, insert a hyphen (-) between them. For example, the pattern bank—loan .* fee is interpreted as the Boolean expression:
((bank PRECEDES loan WITHIN 1) AND (loan AND fee))
Example 4
The pattern %install% .* %problem% matches input with install (or expansions) and problem (or expansions).
Example 5
The pattern "error"—57 matches input with the literal string “error” preceding the number 57.
Example 6
The pattern %myproduct% matches input with any expansion of a client’s product line called myproduct.
