It is certain that Brian is a swan. It is unlikely that John picked up the milk. There is a better than even chance that Julius is a lion. Chances are about even that if either 'John picked up the milk' or 'Julius is a lion' but not both then Greg is yellow. It is almost certain that if 'Brian is a swan' or 'John picked up the milk' or both then Emily is a mouse. It is certain that if 'Brian is a swan and Julius is a lion' then Sandra left the milk.
It is highly unlikely that 'Emily is a mouse' or 'Sandra left the milk' or both.
It is certain that 'Emily is a mouse' or 'Sandra left the milk' or both.
It is highly unlikely that 'Emily is a mouse' 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
  1.0::factA.
  0.2::factB.
  0.6::factC.
  %hop1
  0.5::factX:-xor(factB,factC).
  0.95::factY:-or(factA,factB).
  1.0::factZ:-and(factA,factC).

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

  query(conclusion).
  
'Emily is a mouse' or 'Sandra left the milk' or both.