context: It is impossible that John took the football. It is probably the case that Mary dropped the apple. It is probably the case that Greg is a swan. It is unlikely that if either 'Greg is a swan' or 'Mary dropped the apple' but not both then Sandra left the apple. There is almost no chance that if 'John took the football' or 'Greg is a swan' or both then Bernhard is yellow. It is highly unlikely that if 'John took the football and Greg is a swan' then Bill went to the kitchen.
hypothesis: It is certain that 'Bernhard is yellow' or 'Sandra left the apple' or both.
valid_hypothesis: Chances are slight that 'Bernhard is yellow' or 'Sandra left the apple' or both.
invalid_hypothesis: It is certain that 'Bernhard is yellow' or 'Sandra left the apple' 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
    0.0::factA.
    0.7::factB.
    0.7::factC.
    %hop1
    0.2::factX:-xor(factC,factB).
    0.02::factY:-or(factA,factC).
    0.05::factZ:-and(factA,factC).
  
    %hop2
    conclusion:-or(factY,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is yellow' or 'Sandra left the apple' or both.