Chances are slight that Jessica is a sheep. There is a better than even chance that Fred discarded the apple. Chances are slight that Julius is a swan. Chances are about even that if 'Fred discarded the apple' or 'Jessica is a sheep' or both then Gertrude is a mouse. Chances are about even that if 'Julius is a swan and Jessica is a sheep' then John went to the office. There is almost no chance that if either 'Fred discarded the apple' or 'Julius is a swan' but not both then Lily is a swan.
Chances are slight that 'John went to the office' or 'Jessica is a sheep' or both.
Chances are slight that 'John went to the office' or 'Jessica is a sheep' or both.
It is almost certain that 'John went to the office' or 'Jessica is a sheep' 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.
  0.6::factB.
  0.1::factC.
  %hop1
  0.5::factX:-or(factB,factA).
  0.5::factY:-and(factC,factA).
  0.02::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'John went to the office' or 'Jessica is a sheep' or both.