WORDS: OBSERVABLE UNITS OF A LANGUAGE?

• Loosely defined as a lexical unit - there is an agreed upon meaning in a given community.
  
  
• In many languages (e.g., Indo-European), easily observed in the orthographic (writing) system since it is separated by white space.
  
  
• In spoken language, however, there is a segmentation problem: words run together.
  
  
• Syntax: certain facts about word structure and combinatorial possibilities are evident to most native speakers.
  
  
• Paradigmatic: properties related to meaning.
  
  
• Syntagmatic: properties related to constraints imposed by word combinations (grammar).
  
  
• Word-level constraints are the most common form of "domain knowledge" in a speech recognition system.
  
  
• N-gram models are the most common way to implement word-level constraints.
  
  
• N-gram distributions are very interesting!