html - 数学文本中引理、定理等的适当元素？

Question

通常在数学文本中有小的彩色 block 介绍引理、定理、定义或类似内容，然后是证明它的文本。这是一个简短的示例(来自 D. Lay 的 Linear Algebra and Its Applications，第 4 版):

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两个或多个向量的集合

下定理的证明与例3的解法类似，给出细节 在本节末尾。

Theorem 7: Characterization of Linearly Dependent Sets

An indexed set S = {v₁, ..., v_p} of two or more vectors is linearly dependent if and only if at least one of the vectors in S is a linear combination of the others. In fact, if S is linearly dependent and v₁ ≠ 0, then some v_j (with j > 1) is a linear combination of the preceding vectors, v₁, ..., v_j-1.

警告:定理 7 并未说明线性相关集合中的每个向量都是 前面向量的线性组合。线性相关集合中的向量可能 不能是其他向量的线性组合。参见练习题 3。

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用于这样的 block 的正确元素是什么？

经常<blockquote>被使用了(就像我上面所做的那样)，但我觉得这是错误的——它不一定是引语。我可以使用 <div> , 但我想知道是否有适当的语义元素。

Answer 1

我想这取决于您希望如何构建内容。我可以想到多个选项而不是使用 blockquote:

• 使用 figure(和 figcaption 作为标题):

  <figure>
      <figcaption>Theorem 7: Characterization of Linearly Dependent Sets</figcaption>
      <p>
          An indexed set S = {v1, ..., vp} of two or more vectors is linearly  
          dependent if and only if at least one of the vectors in S is a linear  
          combination of the others. In fact, if S is linearly dependent and v1 ≠ 0, 
          then some vj (with j > 1) is a linear combination of the preceding 
          vectors, v1, ..., vj-1.
      </p>
  </figure>
  

• 使用部分:

  <section>
      <h3>Theorem 7: Characterization of Linearly Dependent Sets</h3>
      <p>
          An indexed set S = {v1, ..., vp} of two or more vectors is linearly  
          dependent if and only if at least one of the vectors in S is a linear  
          combination of the others. In fact, if S is linearly dependent and v1 ≠ 0, 
          then some vj (with j > 1) is a linear combination of the preceding 
          vectors, v1, ..., vj-1.
      </p>
  </section>
  

• 使用 dfn(与上述组合):

  <section>
      <dfn title="Characterization of Linearly Dependent Sets">
          Theorem 7: Characterization of Linearly Dependent Sets
      </dfn>
      <p>
          An indexed set S = {v1, ..., vp} of two or more vectors is linearly  
          dependent if and only if at least one of the vectors in S is a linear  
          combination of the others. In fact, if S is linearly dependent and v1 ≠ 0, 
          then some vj (with j > 1) is a linear combination of the preceding 
          vectors, v1, ..., vj-1.
      </p>
  </section>
  

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尽管 figure/figcaption 看起来是一个简单的选择(这本来是我的第一选择)，但在这种特殊情况下它可能不是最好的选择。根据documentation (我突出显示的粗体部分):

The figure element represents a unit of content, optionally with a caption, that is self-contained, that is typically referenced as a single unit from the main flow of the document, and that can be moved away from the main flow of the document without affecting the document’s meaning.

就定理而言，将图形 移离主流实际上会影响文档的含义。所以我可能会选择最后一个选项(section + dfn)。

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无论如何，无论您的最终选择是什么，最好添加属性 role="definition" 和 aria-labelledby 来指定该部分实际上是一个definition of a term or concept并指向定理标题。

例如:

<section>
    <dfn id="theorem7" title="Characterization of Linearly Dependent Sets">
        Theorem 7: Characterization of Linearly Dependent Sets
    </dfn>
    <p role="definition" aria-labelledby="theorem7">
        An indexed set S = {v1, ..., vp} of two or more vectors is linearly  
        dependent if and only if at least one of the vectors in S is a linear  
        combination of the others. In fact, if S is linearly dependent and v1 ≠ 0, 
        then some vj (with j > 1) is a linear combination of the preceding 
        vectors, v1, ..., vj-1.
    </p>
</section>