A rule is called floor if all of its atoms (head and entire body) are ground. A floor rule R1 is really a ground instance of An additional rule R2 if R1 is the results of a substitution of constants for every one of the variables in R2. The Herbrand https://integratedmanagementsyste61481.blogdon.net/not-known-factual-statements-about-datalog-49937808