“…If (a 1 , b 1 ) and (a 2 , b 2 ) are two such pairs which are bi-freely independent with respect to ϕ, then µ (a 1 +a 2 ,b 1 +b 2 ) depends only on µ (a 1 ,b 1 ) and µ (a 2 ,b 2 ) and is called the additive bi-free convolution of µ (a 1 ,b 1 ) and µ (a 2 ,b 2 ) , denoted µ (a 1 ,b 1 ) ⊞⊞µ (a 2 ,b 2 ) . Likewise, the notion of Boolean independence has been extended to bi-Boolean independence in [10]. However, in the case of bi-Boolean independence, ϕ need not be a state because bi-Boolean product of states is not a state in general.…”