OWL 2，为什么关键公理的语义是特定于命名个体的？
In OWL 2, why is the semantics of key axioms specific to named individuals?
在 OWL 2 的规范中，关于 key axioms 的部分指出：
The semantics of key axioms is specific in that these axioms apply only to individuals explicitly introduced in the ontology by name, and not to unnamed individuals (i.e., the individuals whose existence is implied by existential quantification). This makes key axioms equivalent to a variant of DL-safe rules. Thus, key axioms will typically not affect class-based inferences such as the computation of the subsumption hierarchy, but they will play a role in answering queries about individuals.
然后它继续展示一组公理的示例，这些公理显然会得出结论，但由于该规则，规范不承认。
做出此决定的原因是什么？
在第 1 节中给出了解释。 3.1.4 OWL 2: The Next Step for OWL:
Extending DL-based languages such as OWL 2 with keys, however, poses
both theoretical and practical problems [23]. Therefore, the Working
Group has decided to include a more restricted variant of keys that
can be useful in practice as well as relatively easy to implement,
commonly known as easy keys.
所以他们使用了一种受限制的密钥形式，称为 easy keys，它有一些限制但不会增加推理的最坏情况复杂性：
Thus, the main drawback of easy keys is that they can only produce
consequences about explicit data and are thus relevant mainly for
query answering, whereas the general variant of keys [23] can also
affect the subsumption hierarchy between classes. The main benefits of
easy keys are that adding them to OWL 2 do not increase the worst-case
complexity of reasoning, and that implementing them in the existing
reasoners is relatively straightforward.
简而言之，获得有利的计算复杂度。
虽然表达能力强，但OWL2不能表达任意规则。例如，具有两个变量的规则头不能表示为子class公理，或者包含class表达式的规则体不能用子属性公理描述。扩展OWL2的表达能力，可以使用SWRL规则；但是，这些会使本体无法确定。将 SWRL 规则限制为已知个体，以便每个变量都出现在规则主体的非 DL 原子中，即，使用 DL 安全规则，产生一个非常有表现力但可判定的形式主义。
在 OWL 2 的规范中，关于 key axioms 的部分指出：
The semantics of key axioms is specific in that these axioms apply only to individuals explicitly introduced in the ontology by name, and not to unnamed individuals (i.e., the individuals whose existence is implied by existential quantification). This makes key axioms equivalent to a variant of DL-safe rules. Thus, key axioms will typically not affect class-based inferences such as the computation of the subsumption hierarchy, but they will play a role in answering queries about individuals.
然后它继续展示一组公理的示例，这些公理显然会得出结论，但由于该规则，规范不承认。
做出此决定的原因是什么？
在第 1 节中给出了解释。 3.1.4 OWL 2: The Next Step for OWL:
Extending DL-based languages such as OWL 2 with keys, however, poses both theoretical and practical problems [23]. Therefore, the Working Group has decided to include a more restricted variant of keys that can be useful in practice as well as relatively easy to implement, commonly known as easy keys.
所以他们使用了一种受限制的密钥形式，称为 easy keys，它有一些限制但不会增加推理的最坏情况复杂性：
Thus, the main drawback of easy keys is that they can only produce consequences about explicit data and are thus relevant mainly for query answering, whereas the general variant of keys [23] can also affect the subsumption hierarchy between classes. The main benefits of easy keys are that adding them to OWL 2 do not increase the worst-case complexity of reasoning, and that implementing them in the existing reasoners is relatively straightforward.
简而言之，获得有利的计算复杂度。
虽然表达能力强，但OWL2不能表达任意规则。例如，具有两个变量的规则头不能表示为子class公理，或者包含class表达式的规则体不能用子属性公理描述。扩展OWL2的表达能力，可以使用SWRL规则；但是，这些会使本体无法确定。将 SWRL 规则限制为已知个体，以便每个变量都出现在规则主体的非 DL 原子中，即，使用 DL 安全规则，产生一个非常有表现力但可判定的形式主义。