I'm not sure what your question is.
Pairwise only refers to sets of two random variables.
You have four sets.
Hello,
We must have :
P(A^B)=P(A)P(B)
P(A^C)=P(A)P(C)
P(A^D)=P(A)P(D)
etc
.
.
.
P(A^B^C)=P(A)P(B)P(C)
P(A^B^D)=P(A)P(B)P(D)
P(A^C^D)=P(A)P(C)P(D)
P(B^C^D)=P(B)P(C)P(D)
P(A^B^C^D)= P(A)P(B)P(C)P(D)
In other words, you have to test the formula for any "subset" of {A,B,C,D}