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块介绍引理、定理、定义或类似内容，然后是证明它的文本。这是一个简短的例子（来自 D. Lay 的 Linear Algebra and Its Applications，第 4 版）：

两个或多个向量的集合

下定理的证明与例3的解法类似，给出详细说明在本节末尾。

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 并没有说线性相关集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。

用于这样的块的正确元素是什么？

经常使用<blockquote>（正如我上面所做的），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（标题为 figcaption）：

<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 section:

<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（结合以上）：

<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>

虽然 figure/figcaption 看起来是一个简单的选择（这本来是我的首选），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.

在定理的情况下，将 figure 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).

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 以指定该部分实际上是 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>

Answer 2

对于特定的数学文本，一个选项是 var 元素
<p>An indexed set <var>S</var> = {<var>v<sub>1</sub></var>,...
不仅如此，还可以像 @alvaro 提到的那样使用

- 通过 w3c:
"For mathematics, in particular for anything beyond the simplest of expressions, MathML is more appropriate. However, the var element can still be used to refer to specific variables that are then mentioned in MathML expressions."


<figure>
 <math>
  <mi>a</mi>
  <mo>=</mo>
  <msqrt>
   <msup><mi>b</mi><mn>2</mn></msup>
   <mi>+</mi>
   <msup><mi>c</mi><mn>2</mn></msup>
  </msqrt>
 </math>
 <figcaption>
  Using Pythagoras' theorem to solve for the hypotenuse <var>a</var> of
  a triangle with sides <var>b</var> and <var>c</var>
 </figcaption>
</figure>

http://www.w3.org/TR/html5/text-level-semantics.html#the-var-element

数学文本中引理、定理等的适当元素？

Proper element for lemmas, theorems, etc in mathematical text?

html

element

semantic-markup

两个或多个向量的集合

Theorem 7: Characterization of Linearly Dependent Sets

用于这样的块的正确元素是什么？