Copying overlapping terms

In this paper we discuss techniques to copy overlapping terms. Starting from the classical Cheney-style copying algorithm, we present several refinements that exploit compact terms where a structure’s last argument overlaps with the following structure. Finally, a two pass algorithm is presented that uses less auxiliary space and that exploits all possible overlaps for finite terms. In spite of its using two passes, this algorithm is comparable in speed to single pass algorithms. The presented algorithms have been used and compared within BinProlog.