Quasi-Destructive Graph Unification with Structure-Sharing 
 
 Graph unification remains the most expensive part of unification-based grammar parsing . We focus on one speed-up element in the design of unification algorithms : avoidance of copying of unmodified subgraphs . We propose a method of attaining such a design through a method of structure-sharing which avoids log(d) overheads often associated with structure-sharing of graphs without any use of costly dependency pointers . The proposed scheme eliminates redundant copying while maintaining the quasi-destructive scheme's ability to avoid over copying and early copying combined with its ability to handle cyclic structures without algorithmic additions.  