<<< native
[ EFraction
    NormalFrac
    (EFraction
       NormalFrac
       (ENumber "1")
       (EGrouped [ EIdentifier "y" , ESymbol Bin "+" , ENumber "3" ]))
    (EGrouped [ EIdentifier "y" , ESymbol Bin "+" , ENumber "3" ])
, EFraction
    NormalFrac
    (ENumber "1")
    (EGrouped [ EIdentifier "y" , ESymbol Bin "+" , ENumber "3" ])
, EFraction
    NormalFrac
    (EFraction
       NormalFrac
       (ENumber "1")
       (EGrouped [ EIdentifier "y" , ESymbol Bin "+" , ENumber "3" ]))
    (EGrouped [ EIdentifier "y" , ESymbol Bin "+" , ENumber "3" ])
]
>>> omml
<?xml version='1.0' ?>
<m:oMathPara>
  <m:oMathParaPr>
    <m:jc m:val="center" />
  </m:oMathParaPr>
  <m:oMath>
    <m:f>
      <m:fPr>
        <m:type m:val="bar" />
      </m:fPr>
      <m:num>
        <m:f>
          <m:fPr>
            <m:type m:val="bar" />
          </m:fPr>
          <m:num>
            <m:r>
              <m:t>1</m:t>
            </m:r>
          </m:num>
          <m:den>
            <m:r>
              <m:t>y</m:t>
            </m:r>
            <m:r>
              <m:rPr>
                <m:sty m:val="p" />
              </m:rPr>
              <m:t>+</m:t>
            </m:r>
            <m:r>
              <m:t>3</m:t>
            </m:r>
          </m:den>
        </m:f>
      </m:num>
      <m:den>
        <m:r>
          <m:t>y</m:t>
        </m:r>
        <m:r>
          <m:rPr>
            <m:sty m:val="p" />
          </m:rPr>
          <m:t>+</m:t>
        </m:r>
        <m:r>
          <m:t>3</m:t>
        </m:r>
      </m:den>
    </m:f>
    <m:f>
      <m:fPr>
        <m:type m:val="bar" />
      </m:fPr>
      <m:num>
        <m:r>
          <m:t>1</m:t>
        </m:r>
      </m:num>
      <m:den>
        <m:r>
          <m:t>y</m:t>
        </m:r>
        <m:r>
          <m:rPr>
            <m:sty m:val="p" />
          </m:rPr>
          <m:t>+</m:t>
        </m:r>
        <m:r>
          <m:t>3</m:t>
        </m:r>
      </m:den>
    </m:f>
    <m:f>
      <m:fPr>
        <m:type m:val="bar" />
      </m:fPr>
      <m:num>
        <m:f>
          <m:fPr>
            <m:type m:val="bar" />
          </m:fPr>
          <m:num>
            <m:r>
              <m:t>1</m:t>
            </m:r>
          </m:num>
          <m:den>
            <m:r>
              <m:t>y</m:t>
            </m:r>
            <m:r>
              <m:rPr>
                <m:sty m:val="p" />
              </m:rPr>
              <m:t>+</m:t>
            </m:r>
            <m:r>
              <m:t>3</m:t>
            </m:r>
          </m:den>
        </m:f>
      </m:num>
      <m:den>
        <m:r>
          <m:t>y</m:t>
        </m:r>
        <m:r>
          <m:rPr>
            <m:sty m:val="p" />
          </m:rPr>
          <m:t>+</m:t>
        </m:r>
        <m:r>
          <m:t>3</m:t>
        </m:r>
      </m:den>
    </m:f>
  </m:oMath>
</m:oMathPara>