boundary-symbol

Symbols used in TRANSFORMATIONAL GRAMMAR to indicate the boundaries between STRUCTURAL UNITS, e.g. the ELEMENTS of a STRING (+), or the boundaries of strings (#), e.g. # the+man+pres+have+en-+kick+the+ball#. The notion has a central role in some models of PHONOLOGY, where the DOMAINS of phonological RULES can be expressed in terms of phonological boundary symbols. Boundary strength is quantitative, expressed by the number of symbols present. A given phonological rule specifies only the minimal boundary strength across which it cannot apply.