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<mml:mi>a</mml:mi>
<mml:mo>,</mml:mo>
<mml:mi>b</mml:mi>
<mml:mo>&#8712;</mml:mo>
<mml:mi mathvariant="double-struck">C</mml:mi>
<mml:mo stretchy="false">(</mml:mo>
<mml:mi mathvariant="double-struck">R</mml:mi>
<mml:mo stretchy="false">/</mml:mo>
<mml:mi>T</mml:mi>
<mml:mi mathvariant="double-struck">Z</mml:mi>
<mml:mo>,</mml:mo>
<mml:mi mathvariant="double-struck">R</mml:mi>
<mml:mo stretchy="false">)</mml:mo>
</mml:math>