It is improbable that Sandra left the milk. It is improbable that Greg is a lion. There is a very good chance that John moved to the office. Chances are slight that if 'Sandra left the milk and John moved to the office' then Brian is a rhino. It is likely that if 'Greg is a lion and Sandra left the milk' then Jessica is a cat. Chances are about even that if 'John moved to the office' or 'Greg is a lion' or both then Julius is yellow.
Chances are slight that 'Brian is a rhino' or 'Greg is a lion' or both.
Chances are slight that 'Brian is a rhino' or 'Greg is a lion' or both.
It is probably the case that 'Brian is a rhino' or 'Greg is a lion' 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.
  0.1::factB.
  0.8::factC.
  %hop1
  0.1::factX:-and(factA,factC).
  0.7::factY:-and(factB,factA).
  0.5::factZ:-or(factC,factB).

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

  query(conclusion).
  
'Brian is a rhino' or 'Greg is a lion' or both.