We then go on to compare the current approach with that of some other theories with similar aims : the `` standard '' version of quasi-logical form implemented in the Core Language Engine , as rationally reconstructed by Alshawi and Crouch ( 1992 ) and Crouch and Pulman ( 1994 ) ; underspecified Discourse Representation Theory ( Reyle 1993 ) ; and the `` glue language '' approach of Dalrymple et al. ( 1996 ) .