Digital Signal Processing Reference
In-Depth Information
Figure 5-3.
Example of ScenarioXML: common arc.
Figure 5-4.
Example of DialogXML.
A more complicated example is shown in Fig. 5-5. There are two flows of the
main dialog and two types of common arcs. In this figure, every arc is related to a
specific grammar. It means that the control of the dialog flow is tightly related with
grammar selection. This principle is described in detail in the following section.
4.
GRAMMARS AND LEXICONS
In VoiceXML, a
grammar
specifies (for a particular dialog state) the set of
allowed words and the structure(s) of allowable sentences using those words
(defined in terms of legal part-of-speech sequences). To avoid confusion, we
refer to the former aspect of VoiceXML grammars as a “lexicon”, and the
latter aspect as a “grammar”; the pairing of a lexicon and a grammar in
VoiceXML is referred to as a “<grammar>.” A <grammar> operates on an
input to capture a set of attribute-value pairs from the user's utterance. One
