  Adapting rule sets to different settings, yet avoiding uncontrolled
proliferation of variations, is a key challenge of rule management. One
fundamental concept to foster reuse and simplify adaptation is inheritance.
Building on rule modules, i.e., rule sets with input and output schema, we
formally define inheritance of rule modules by incremental modification in
single inheritance hierarchies. To avoid uncontrolled proliferation of
modifications, we introduce formal modification restrictions which flexibly
regulate the degree to which a child module may be modified in comparison to
its parent. As concrete rule language, we employ Datalog+/- which can be
regarded a common logical core of many rule languages. We evaluate the approach
by a proof-of-concept prototype.
