The paper studies defeasible reasoning in rule-based systems, in particular about legal norms and contracts. We identify rule modifiers that specify how rules interact and how they can be overridden. We then define rule transformations that eliminate these modifiers, leading in the end to a translation of rules to formulas. For reasoning with and about rules, we contrast two approaches, one in a classical logic with SMT solvers as proof engines, one in a non-monotonic logic with Answer Set Programming solvers.

翻译：论文研究了基于规则的系统中不可行的推理,特别是关于法律规范和合同的推理。我们确定了规则的修改者,具体规定规则如何相互作用,如何推翻规则。然后我们定义规则的转变,消除这些修改者,最终将规则转换成公式。关于规则的推理和规则的推理,我们比较了两种方法,一种是传统逻辑,一种是SMT解答者作为验证引擎,一种是非分子逻辑,一种是“回答设置”编程求解者。