The functional notion of "topic" or "topicality" has suffered, traditionally, from two distinct drawbacks. First, it has remained largely ill defined or intuitively defined. And second, quite often its definition boiled down to structure-dependent circularity. This volume represents a major departure from past practices, without rejecting both their intuitive appeal and the many good results yielded by them. First, "topic" and "topicality" are re-analyzed...