There's no negation in SWI-Prolog's tabling. As not/one works by using a cut, one may possibly end up with incomplete tables and incorrect final results. AleksejAleksej 22.9k66 gold badges3636 silver badges3838 bronze badges one Thanks but my example earlier mentioned is simplified, I ought to use execute instant (as https://executivetable92456.blogsvila.com/32377541/what-does-executive-tabletop-coffee-machines-mean