XPath, CTL and the modal logics proposed by Blackburn et al, Palm and Kracht are variable free formalisms to describe and reason about (finite) trees. XPath expressions evaluated at the root of a tree correspond to existential positive modal formulas. The models of XPath expressions are finite ordered trees, or in the presence of XML's ID/IDREF mechanism graphs. The ID/IDREF mechanism can be seen as a device for naming nodes. Naming devices have been studied in hybrid logic by nominals. We add nominals to the modal logic of Palm and interpret the language on directed acyclic graphs. We give an algorithm which decides the consequence problem of this logic in exponential time. This yields a complexity result for query containment of the corresponding extension of XPath.
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机译:XPath,CTL和Blackburn等人,Palm和Kracht提出的模态逻辑都是无变量的形式主义,用于描述(有限)树并对其进行推理。在树的根部评估的XPath表达式对应于存在的正模态公式。 XPath表达式的模型是有限顺序的树,或者存在XML的ID / IDREF机制图。 ID / IDREF机制可以看作是用于命名节点的设备。命名设备已经通过标称在混合逻辑中进行了研究。我们将标称添加到Palm的模态逻辑中,并在有向无环图上解释该语言。我们给出了一种算法,该算法在指数时间内决定了该逻辑的后果问题。这会为查询包含XPath的相应扩展产生复杂性结果。
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机译:转换± Sup> [m j Sub>] f(+/-) min Sub>→± Sup> U DAG的方法 Sub> f([[± Sup> m i Sub>])最小化位置符号参数的结构± Sup> [m j Sub >] f(+/-) min Sub>三进制数系统f(+ 1,0,-1)进入模拟电压参数± Sup> U DAC Sub> f([m j Sub>])(俄罗斯逻辑版本)