We believe that Winona is a sheep. It is impossible that Julius is gray. There is a very good chance that Mary put down the apple. It is probably the case that if either 'Winona is a sheep' or 'Mary put down the apple' but not both then Sandra dropped the milk. It is likely that if 'Mary put down the apple and Julius is gray' then Greg is a rhino. We doubt that if 'Winona is a sheep' or 'Julius is gray' or both then Fred is in the office.
We doubt that 'Winona is a sheep' or 'Julius is gray' or both.
We believe that 'Winona is a sheep' or 'Julius is gray' or both.
We doubt that 'Winona is a sheep' or 'Julius is gray' 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
  0.75::factA.
  0.0::factB.
  0.8::factC.
  %hop1
  0.7::factX:-xor(factA,factC).
  0.7::factY:-and(factC,factB).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Winona is a sheep' or 'Julius is gray' or both.