while the reverse is true of sheep. Similarly, the operators eat, devour, chew and swallow differ in meaning to the extent that the arguments they select and the operators that select them differ. Operator grammar predicts that the information carried by a sentence is the accumulation of contributions of each argument and operator. The increment of information that a given word adds to a new sentence is determined by how it was used before. In turn, new usages stretch or even alter the information content associated with a word. Because this process is based on high frequency usage, the meanings of words are relatively stable over time, but can change in accordance with the needs of a linguistic community. Bibliography Dependency grammar Information theory