Given the mathml <math xmlns="http://www.w3.org/1998/Math/MathML"> <apply> <times /> <ci>k1</ci> <ci>k2</ci> <ci>S1</ci> </apply> </math> the latex conversion is '$\mathrm{k1}\mathrm{k2}\mathrm{S1}$' this renders to k1k2S1 ie there is no spacing between the symbols.
Given the mathml
k1 k2 S1the latex conversion is
'$\mathrm{k1}\mathrm{k2}\mathrm{S1}$'
this renders to
k1k2S1
ie there is no spacing between the symbols.