It is unlikely that Jessica is a cat. There is a better than even chance that Brian is a rhino. Chances are slight that Sandra dropped the milk. It is improbable that if either 'Brian is a rhino' or 'Jessica is a cat' but not both then John left the football. It is improbable that if either 'Sandra dropped the milk' or 'Jessica is a cat' but not both then Greg is a lion. Chances are about even that if 'Jessica is a cat and Brian is a rhino' then Julius is a frog.
It is unlikely that 'Sandra dropped the milk' or 'John left the football' or both.
It is unlikely that 'Sandra dropped the milk' or 'John left the football' or both.
It is probable that 'Sandra dropped the milk' or 'John left the football' or both.

  and(A,B) :- A,B.
  or(A,B) :- A;B.
  nand(A,B) :- not(and(A,B)).
  nor(A,B) :- not(or(A,B)).
  xor(A,B) :- or(A,B), nand(A,B).

  %hop0
  0.2::factA.
  0.6::factB.
  0.1::factC.
  %hop1
  0.1::factX:-xor(factB,factA).
  0.1::factY:-xor(factC,factA).
  0.5::factZ:-and(factA,factB).

  %hop2
  conclusion:-or(factC,factX).

  query(conclusion).
  
'Sandra dropped the milk' or 'John left the football' or both.