MathML for math symbol subset?

Hi, there:

Do you know any browser can handle:

S ={s i ,...,s N } [i, N should be subset]
(s 1 , S - s 1 )     [1 should be subset]

when they were markuped as:

<MI>S<D>= {<MI>s<MIV>i<D>, ..., <MI>s<MIV>N<D>}
(<MI>s<MV>1<D>, <MI>S<F128D> - <F255MI>s<MV>1<D>

Are the markups valid MathML?  In addition to HTML gif or pdf as
embedded objects for rendering, do you know any other ways to display
math symbols like these without invoking any application?

My wish would be a browser that could handle Math symbol display
as good and easy as .pdf.   Any help appreciated!

Amanda Xu