This manual describes version 2.7.19 of SWI-Prolog. SWI-Prolog has been used now for several years. The application range includes Prolog course material, meta-interpreters, simulation of parallel Prolog, learning systems, natural language processing and two large workbenches for knowledge engineering. Although we experienced rather obvious and critical bugs can remain unnoticed for a remarkable long period, we can assume the basic Prolog system is fairly stable. Bugs can be expected in infrequently used builtin predicates.
Some bugs are known to the author. They are described as footnotes in this manual.