context: It is certain that Sandra got the football. It is highly likely that Julius is a rhino. We believe that Bernhard is a swan. It is probably the case that if 'Julius is a rhino and Bernhard is a swan' then Greg is yellow. It is highly unlikely that if 'Julius is a rhino' or 'Bernhard is a swan' or both then Brian is green. It is almost certain that if 'Bernhard is a swan and Julius is a rhino' then Daniel dropped the apple.
hypothesis: It is probably not the case that either 'Bernhard is a swan' or 'Sandra got the football' but not both.
valid_hypothesis: It is probably not the case that either 'Bernhard is a swan' or 'Sandra got the football' but not both.
invalid_hypothesis: It is probably the case that either 'Bernhard is a swan' or 'Sandra got the football' but not 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
    1.0::factA.
    0.9::factB.
    0.75::factC.
    %hop1
    0.7::factX:-and(factB,factC).
    0.05::factY:-or(factB,factC).
    0.95::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-xor(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Bernhard is a swan' or 'Sandra got the football' but not both.