This manual describes version 4.0.11 of SWI-Prolog. SWI-Prolog has been used now for many 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 assume the basic Prolog system is fairly stable. Bugs can be expected in infrequently used built-in predicates.
Some bugs are known to the author. They are described as footnotes in this manual.