context: It is unlikely that Sandra got the football. It is certain that Mary went to the kitchen. It is impossible that Jessica is a sheep. Chances are about even that if either 'Sandra got the football' or 'Jessica is a sheep' but not both then Greg is a swan. It is almost certain that if either 'Jessica is a sheep' or 'Sandra got the football' but not both then Fred dropped the milk. It is almost certain that if either 'Mary went to the kitchen' or 'Jessica is a sheep' but not both then Bernhard is green.
hypothesis: It is unlikely that 'Sandra got the football' or 'Greg is a swan' or both.
valid_hypothesis: It is unlikely that 'Sandra got the football' or 'Greg is a swan' or both.
invalid_hypothesis: It is almost certain that 'Sandra got the football' or 'Greg is a swan' or both.
problog: 
    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
    0.2::factA.
    1.0::factB.
    0.0::factC.
    %hop1
    0.5::factX:-xor(factA,factC).
    0.95::factY:-xor(factC,factA).
    0.95::factZ:-xor(factB,factC).
  
    %hop2
    conclusion:-or(factA,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Sandra got the football' or 'Greg is a swan' or both.