data/mathematical/55.mml
<math xmlns='http://www.w3.org/1998/Math/MathML' display='inline'><semantics><mrow><msub><mo>∑</mo> <mi>x</mi></msub><msub><mo>∑</mo> <mi>y</mi></msub><mi>I</mi><mo stretchy="false">(</mo><mi>x</mi><mo>,</mo><mi>y</mi><mo stretchy="false">)</mo></mrow><annotation encoding='application/x-tex'>\sum_x \sum_y I(x,y)</annotation></semantics></math>