It is almost certain that Emily is a mouse. We believe that Julius is a rhino. It is unlikely that Lily is a lion. It is unlikely that if either 'Julius is a rhino' or 'Lily is a lion' but not both then Brian is a frog. It is highly unlikely that if 'Emily is a mouse and Lily is a lion' then Bernhard is a swan. It is probably not the case that if 'Lily is a lion and Julius is a rhino' then John dropped the apple.
It is highly unlikely that 'John dropped the apple' or 'Bernhard is a swan' or both.
It is highly unlikely that 'John dropped the apple' or 'Bernhard is a swan' or both.
We believe that 'John dropped the apple' or 'Bernhard is a swan' 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
  0.95::factA.
  0.75::factB.
  0.2::factC.
  %hop1
  0.2::factX:-xor(factB,factC).
  0.05::factY:-and(factA,factC).
  0.25::factZ:-and(factC,factB).

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

  query(conclusion).
  
'John dropped the apple' or 'Bernhard is a swan' or both.