What are the rules for interpreting aggregate mathematical functions (min, max, sum, product)?

At first glance, the semantics of these functions seem unclear because it requires symbols do have different meaning depending on their context. Example:

<math xmlns="http://www.w3.org/1998/Math/MathML">
  <apply>
    <divide/>
    <ci> task1_____PX </ci>
    <apply>
      <csymbol definitionURL="http://sed-ml.org/#max" encoding="text">max</csymbol>
      <ci> task1_____PX </ci>
    </apply>
  </apply>
</math>

Questions

Are symbols always interpreted to be vectors inside these aggregate functions?
Can these aggregate functions be used to calculate the min or max of two different symbols? If so, how is one intended to communicate this should be a scalar rather than a vector calculation? If the symbols are vectors, is this intended to be an element-wide computation or operate over the entire vectors?
How are these functions intended to be executed for results of repeated tasks which are multidimensional? or results of spatial simulations which could be multi-dimensional?
Why are these defined with http://sed-ml.org/#max rather than MathML? The specifications suggest these are MathML functions, but this suggests otherwise. This isn't ideal because the SED-ML specifications don't clearly define the semantics of these functions.

<math xmlns="http://www.w3.org/1998/Math/MathML">
    <apply>
      <csymbol definitionURL="http://sed-ml.org/#max" encoding="text">max</csymbol>
      <ci> task1_____PX </ci>
      <ci> task1_____PY </ci>
    </apply>
</math>

SED-ML / sed-ml

What are the rules for interpreting aggregate mathematical functions (min, max, sum, product)? #152