SICStus
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SICStus is an implementation of Prolog.
Other implementations of Prolog.
SICStus Prolog is a state-of-the-art, ISO standard compliant, Prolog development system. It is battle tested, and has been used by many high profile projects.
SICStus Prolog is proprietary and not free for personal or commercial use. An evaluation trial is available at the SICStus website.