There is no negation in SWI-Prolog's tabling. As not/1 makes use of a Slice, one may perhaps end up with incomplete tables and incorrect effects. AleksejAleksej 22.9k66 gold badges3636 silver badges3838 bronze badges 1 Many thanks but my example over is simplified, I need to use execute fast (as https://milohmnfe.canariblogs.com/fascination-about-executive-compensation-table-47291695