Xslt 基于其祖先在其祖先的第一个子元素中的存在删除元素

请根据元素（msubup）在其（msubup）祖先（msub或msup）的第一个子元素（position=1）中的祖先（msubup）来建议如何删除元素（mstyle）

请参阅我在XML和XSLT中的注释，以便快速参考。（XSLT2）

输入XML:

<root>
<math>

<msubsup>
    <mrow><mi>H</mi></mrow>
    <mstyle width="70%"><mrow><mn>2</mn></mrow></mstyle><!-- mstyle to retained because NO ancestor like 'msub' or 'msup' found for msubsup--> 
</msubsup>

<mrow><mtext>The text 1</mtext></mrow>

<msub>
    <mrow><!--First Child to msub-->
        <msubsup>
            <mi>K</mi>
            <mstyle width="70%"><mn>2</mn></mstyle><!--mstyle required to remove because   msubsup found in 'msub's first child area -->
            <mo>+</mo>
        </msubsup>
    </mrow>
    <mrow><mn>2</mn></mrow><!--second Child to msub-->
</msub>

<mrow><mtext>The text 2</mtext></mrow>

<msup>
    <mrow><!--First Child to msup-->
        <mrow>
            <msubsup>
                <mrow><mi>K</mi></mrow>
                <mstyle width="70%"><mrow><mn>2</mn></mrow></mstyle><!--mstyle required to remove because   msubsup found in 'msup's first child area -->
                <mrow><mo>+</mo></mrow>
            </msubsup>
        </mrow>
    </mrow>
    <mrow><mn>2</mn></mrow><!--second Child to msup-->
</msup>

<mrow><mtext>The text 3</mtext></mrow>

<msub>
    <mrow><mn>A</mn></mrow><!--First Child to msub-->
    <mrow><!--second Child to msub-->
        <mrow>
            <msubsup>
                <mrow><mi>K</mi></mrow>
                <mstyle width="70%"><mrow><mn>2</mn></mrow></mstyle><!--mstyle required to RETAIN because   msubsup found in 'msub's SECOND child area -->
                <mrow><mo>+</mo></mrow>
            </msubsup>
        </mrow>
    </mrow>
</msub>

</math>

</root>

H
2.
案文1
K
2.
+
2.
案文2
K
2.
+
2.
案文3
A.
K
2.
+

XSLT:

所需输出：

<root>
<math>
<msubsup>
    <mrow><mi>H</mi></mrow>
    <mstyle width="70%"><mrow><mn>2</mn></mrow></mstyle><!-- mstyle to retained because NO ancestor like 'msub' or 'msup' found for msubsup--> 
</msubsup>
<mrow><mtext>The text 1</mtext></mrow>

<msub>
    <mrow>
        <msubsup>
            <mi>K</mi>
            <mn>2</mn>
            <mo>+</mo>
        </msubsup>
    </mrow>
    <mrow><mn>2</mn></mrow>
</msub>
<mrow><mtext>The text 2</mtext></mrow>

<msup>
    <mrow>
        <mrow>
            <msubsup>
                <mrow><mi>K</mi></mrow>
                <mrow><mn>2</mn></mrow>
                <mrow><mo>+</mo></mrow>
            </msubsup>
        </mrow>
    </mrow>
    <mrow><mn>2</mn></mrow>
</msup>
<mrow><mtext>The text 3</mtext></mrow>

<msub>
    <mrow><mn>A</mn></mrow>
    <mrow>
        <mrow>
            <msubsup>
                <mrow><mi>K</mi></mrow>
                <mstyle width="70%"><mrow><mn>2</mn></mrow></mstyle><!--Required retain mstyle here, bcs msubsup found in second child of msub or msup-->
                <mrow><mo>+</mo></mrow>
            </msubsup>
        </mrow>
    </mrow>
</msub>

</math>


</root>

H
2.
案文1
K
2.
+
2.
案文2
K
2.
+
2.
案文3
A.
K
2.
+

---

应删除元素mstyle，但保留内部元素，谢谢您的建议

<root>
<math>
<msubsup>
    <mrow><mi>H</mi></mrow>
    <mstyle width="70%"><mrow><mn>2</mn></mrow></mstyle><!-- mstyle to retained because NO ancestor like 'msub' or 'msup' found for msubsup--> 
</msubsup>
<mrow><mtext>The text 1</mtext></mrow>

<msub>
    <mrow>
        <msubsup>
            <mi>K</mi>
            <mn>2</mn>
            <mo>+</mo>
        </msubsup>
    </mrow>
    <mrow><mn>2</mn></mrow>
</msub>
<mrow><mtext>The text 2</mtext></mrow>

<msup>
    <mrow>
        <mrow>
            <msubsup>
                <mrow><mi>K</mi></mrow>
                <mrow><mn>2</mn></mrow>
                <mrow><mo>+</mo></mrow>
            </msubsup>
        </mrow>
    </mrow>
    <mrow><mn>2</mn></mrow>
</msup>
<mrow><mtext>The text 3</mtext></mrow>

<msub>
    <mrow><mn>A</mn></mrow>
    <mrow>
        <mrow>
            <msubsup>
                <mrow><mi>K</mi></mrow>
                <mstyle width="70%"><mrow><mn>2</mn></mrow></mstyle><!--Required retain mstyle here, bcs msubsup found in second child of msub or msup-->
                <mrow><mo>+</mo></mrow>
            </msubsup>
        </mrow>
    </mrow>
</msub>

</math>


</root>

<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
    <xsl:output method="xml" indent="yes"/>

    <!-- The identity transform. -->
    <xsl:template match="@* | node()">
        <xsl:copy>
            <xsl:apply-templates select="@* | node()"/>
        </xsl:copy>
    </xsl:template>

    <!-- Match mstyle and output nothing if its msubsup parent is a descendent
         of the first child of msub or msup.-->
    <xsl:template match="msub/*[1]//msubsup/mstyle|msup/*[1]//msubsup/mstyle">
        <!-- Still want to output children of mstyle though. -->
        <xsl:apply-templates select="node()"/>
    </xsl:template>
</xsl:stylesheet>