  The design and implementation of an incremental copying heap garbage
collector for WAM-based Prolog systems is presented. Its heap layout consists
of a number of equal-sized blocks. Other changes to the standard WAM allow
these blocks to be garbage collected independently. The independent collection
of heap blocks forms the basis of an incremental collecting algorithm which
employs copying without marking (contrary to the more frequently used mark&copy
or mark&slide algorithms in the context of Prolog). Compared to standard
semi-space copying collectors, this approach to heap garbage collection lowers
in many cases the memory usage and reduces pause times. The algorithm also
allows for a wide variety of garbage collection policies including generational
ones. The algorithm is implemented and evaluated in the context of hProlog.
