At least in the context of the headline, you can assume any mathematician being offered a $1m prize is likely to be an expert. In wider usage, I guess you coul

At least in the context of the headline, you can assume any mathematician being offered a $1m prize is likely to be an expert. In wider usage, I guess you could say "Math expert" to distinguish between students and professionals, but it's still as clear as mud because it doesn't state which field of mathematics the person is an expert in.