I'm dealing better with probability now, but now I've faced an weird naming:
$P(\{a2, a3\}) = 2*P(a1)$
I'm guessing this {} stands for the union of both a2 and a3, am I right ?, how would I find a1 now as I don't have any value of the functions, would $P(a1) = \dfrac{P(\{a2, a3\})}{2}$ right ?
Thanks in advance;