There is little chance that Julius is a lion. It is probably not the case that Greg is a swan. There is a very good chance that Sandra left the milk. It is probable that if 'Greg is a swan' or 'Julius is a lion' or both then Bernhard is a rhino. There is little chance that if 'Julius is a lion and Greg is a swan' then Brian is a frog. It is likely that if 'Sandra left the milk' or 'Greg is a swan' or both then John went to the office.
There is a very good chance that 'Brian is a frog' or 'Sandra left the milk' or both.
There is a very good chance that 'Brian is a frog' or 'Sandra left the milk' or both.
We doubt that 'Brian is a frog' or 'Sandra left the milk' 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
  0.1::factA.
  0.25::factB.
  0.8::factC.
  %hop1
  0.7::factX:-or(factB,factA).
  0.1::factY:-and(factA,factB).
  0.7::factZ:-or(factC,factB).

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

  query(conclusion).
  
'Brian is a frog' or 'Sandra left the milk' or both.