Question

Select all of the following statements that are true for all joint distributions over X and
Y?
P(x,y)=P(x)P(y)
P(x,y)=P(x|y)P(y)
P(x,y)=P(x|y)P(y|x)
P(x)=∑
yP(x|y)
P(x)=∑
yP(x,y)
None of the above.