context: Chances are about even that Julius is a rhino. It is improbable that Emily is a mouse. There is almost no chance that Brian is white. It is highly unlikely that if either 'Emily is a mouse' or 'Julius is a rhino' but not both then Lily is a lion. We believe that if either 'Brian is white' or 'Julius is a rhino' but not both then Sandra dropped the milk. It is certain that if 'Emily is a mouse and Brian is white' then Gertrude is a sheep.
hypothesis: It is almost certain that 'Brian is white and Lily is a lion'.
valid_hypothesis: It is impossible that 'Brian is white and Lily is a lion'.
invalid_hypothesis: It is almost certain that 'Brian is white and Lily is a lion'.
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
    0.5::factA.
    0.1::factB.
    0.02::factC.
    %hop1
    0.05::factX:-xor(factB,factA).
    0.75::factY:-xor(factC,factA).
    1.0::factZ:-and(factB,factC).
  
    %hop2
    conclusion:-and(factC,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is white and Lily is a lion'.