context: It is highly unlikely that Jessica is a sheep. There is a very good chance that Mary dropped the milk. It is likely that John put down the apple. There is little chance that if either 'Jessica is a sheep' or 'Mary dropped the milk' but not both then Sandra is in the kitchen. There is a better than even chance that if 'Mary dropped the milk and John put down the apple' then Julius is a swan. There is almost no chance that if 'John put down the apple' or 'Mary dropped the milk' or both then Bernhard is a rhino.
hypothesis: It is certain that 'Julius is a swan' or 'Sandra is in the kitchen' or both.
valid_hypothesis: Chances are about even that 'Julius is a swan' or 'Sandra is in the kitchen' or both.
invalid_hypothesis: It is certain that 'Julius is a swan' or 'Sandra is in the kitchen' 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
    0.05::factA.
    0.8::factB.
    0.7::factC.
    %hop1
    0.1::factX:-xor(factA,factB).
    0.6::factY:-and(factB,factC).
    0.02::factZ:-or(factC,factB).
  
    %hop2
    conclusion:-or(factY,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is a swan' or 'Sandra is in the kitchen' or both.