Joint probability is usually expressed with a comma:
$P(A=a, B=b) $ meaning: The probability of random variable A having value a and random variable B having value b
But what would be the notation of the disjunction? The probability of random variable A having value a or random variable B having value b? $P(A=a ? B=b) = P(A=a) + P(B=b) - P(A=a, B=b) $
I could use the logical 'or' $P(A=a \vee B=b)$ but then shouldnt i also use the logical 'and'?