LingPipe uses a hierarchy of classes to support SBD, as shown in the following diagram:
At the base of this hierarchy is the AbstractSentenceModel class, whose primary method is an overloaded boundaryIndices method. This method returns an integer array of a boundary index where each element of the array represents a sentence boundary.
Derived from this class is the HeuristicSentenceModel class. This class uses a series of possible stops, impossible penultimates, and impossible starts token sets. These were discussed earlier in the Understanding the SBD rules of LingPipe's HeuristicSentenceModel class section.
The IndoEuropeanSentenceModel and MedlineSentenceModel classes are derived from the HeuristicSentenceModel class. They have been trained for English and specialized for medical text, respectively. We will illustrate both of these classes in the following sections.