Despite their formal elegance, implementations of these theories cannot yet handle naturally occurring texts, such as that shown in (1).
the theories aimed at characterizing the constraints that pertain to the structure of unrestricted texts and the computational mechanisms that would enable the derivation of these structures (van Dijk 1972;Zock 1985;Grosz and Sidner 1986;Mann and Thompson 1988;Polanyi 1988Polanyi , 1996Hobbs 1990) are either too informal or incompletely specified to support a fully automatic approach to discourse analysis.