ag-gipp/GoUldI

<math 
  xmlns="http://www.w3.org/1998/Math/MathML">
  <semantics>
    <mrow>
      <mi>f</mi>
      <mo>:</mo>
      <msub>
        <mstyle mathvariant="double-struck">
          <mi>N</mi>
        </mstyle>
        <mn>1</mn>
      </msub>
      <mo stretchy="false">→</mo>
      <msub>
        <mstyle mathvariant="double-struck">
          <mi>N</mi>
        </mstyle>
        <mn>1</mn>
      </msub>
    </mrow>
    <annotation encoding="TeX">f:{\mathbb{N}_{1}}\to{\mathbb{N}_{1}}</annotation>
  </semantics>
</math>