"TM" == Timothy Murphy writes:
>> e.g. Shafarevich groups in algebraic geometry are often denoted
>> with capital cyrillic letter sha - not only in russian literature!
TM> But my serious point is that it seems to me more sensible to use
TM> a macro-name like \shaf rather than arranging for a single input
TM> character to create this output.
if the document input encoding is ascii or some latin-based
(e.g. iso-8859-1), then this is indeed more sensible (no other way),
but if the input encoding is cyrillic (e.g. koi8-r) or UTF-8,
then it may be more natural to just use the keyboard character
(cyrillic letter sha) for that.
(with the mathtext package, it will work)