In this paper, we integrate the defeasible logic of Kraus, Lehmann and Magidor (KLM) with the standpoint logic framework of Gómez Álvarez and Rudolph. This is done with the goal of formally expressing knowledge taking into account multiple (possibly contradicting) viewpoints, which in turn may hold defeasible beliefs. In doing so, we utilise Defeasible Restricted Standpoint Logics (DRSL), introduced by Leisegang et al. Our work expands on previous work by providing a foundational representation result for DRSL semantics and systematically lifting several well-known entailment relations from the propositional case to the standpoint-enhanced setting. In particular, we characterise the semantics for DRSL through a set of KLM-style postulates adapted for the standpoints case. We furthermore provide a means to lift preferential entailment, and the class of entailment relations based on single ranking functions from the purely propositional to the standpoint-enhanced context, including rational and lexicographic closure. We show this can be done equivalently through semantic and algorithmic means. Furthermore, we show that, for each considered form of entailment, the complexity class of entailment checking does not change when moving from propositional KLM to DRSL.

翻译：在本文中，我们将Kraus、Lehmann和Magidor（KLM）的可废止逻辑与Gómez Álvarez和Rudolph的立场逻辑框架相结合。其目标是形式化地表达考虑多个（可能相互矛盾的）视角的知识，而这些视角本身可能持有可废止信念。为此，我们利用了Leisegang等人引入的可废止受限立场逻辑（DRSL）。我们的工作扩展了先前的研究，为DRSL语义提供了基础性的表示结果，并系统地将若干众所周知的蕴涵关系从命题情形提升到立场增强框架中。具体而言，我们通过一套为立场情形调整的KLM风格公设来刻画DRSL的语义。此外，我们提供了一种将优先蕴涵以及基于单一排序函数的蕴涵关系类（包括理性闭包和词典序闭包）从纯命题语境提升到立场增强语境的方法。我们证明这可以通过语义和算法两种等价方式实现。进一步地，我们表明，对于所考虑的每种蕴涵形式，从命题KLM转移到DRSL时，蕴涵检验的复杂度类并未发生变化。