Chances are about even that Greg is a swan. We believe that Julius is a rhino. It is probably not the case that Gertrude is a mouse. It is almost certain that if 'Greg is a swan' or 'Gertrude is a mouse' or both then Daniel took the apple. It is impossible that if 'Greg is a swan and Julius is a rhino' then Lily is white. It is probable that if 'Gertrude is a mouse and Julius is a rhino' then Mary discarded the milk.
There is a better than even chance that 'Gertrude is a mouse' or 'Daniel took the apple' or both.
There is a better than even chance that 'Gertrude is a mouse' or 'Daniel took the apple' or both.
It is impossible that 'Gertrude is a mouse' or 'Daniel took the apple' 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
  0.5::factA.
  0.75::factB.
  0.25::factC.
  %hop1
  0.95::factX:-or(factA,factC).
  0.0::factY:-and(factA,factB).
  0.7::factZ:-and(factC,factB).

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

  query(conclusion).
  
'Gertrude is a mouse' or 'Daniel took the apple' or both.