[infradig]

Well I don't generally consider chess mastery to be a sign of genius. Or maths, or music either. Fundamentally they are not creative, generative activities. There's a reason they are called a prodigy and not a genius. Of course there are the rare genius composer (eg Mozart) or mathematician (eg Euler).

[tuesdayrain]

I consider mastery of anything to be a sign of genius. Someone out there is in the top .001% of skill for underwater basketweaving, and I think they're a genius in that category.

[theoh]

Mathematics is a creative activity, at least at the professional level.