context: It is highly likely that Jessica is a mouse. It is highly unlikely that Julius is yellow. It is probable that Greg is a swan. It is impossible that if either 'Julius is yellow' or 'Greg is a swan' but not both then Sandra grabbed the milk. There is a better than even chance that if either 'Julius is yellow' or 'Greg is a swan' but not both then Brian is a rhino. We believe that if either 'Greg is a swan' or 'Jessica is a mouse' but not both then John moved to the garden.
hypothesis: It is certain that 'Julius is yellow and Brian is a rhino'.
valid_hypothesis: It is impossible that 'Julius is yellow and Brian is a rhino'.
invalid_hypothesis: It is certain that 'Julius is yellow and Brian is a rhino'.
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
    0.9::factA.
    0.05::factB.
    0.7::factC.
    %hop1
    0.0::factX:-xor(factB,factC).
    0.6::factY:-xor(factB,factC).
    0.75::factZ:-xor(factC,factA).
  
    %hop2
    conclusion:-and(factB,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Julius is yellow and Brian is a rhino'.