context: Chances are slight that Brian is a lion. It is improbable that Julius is a swan. It is certain that Greg is a rhino. There is a better than even chance that if 'Julius is a swan and Greg is a rhino' then Lily is a swan. We believe that if 'Julius is a swan' or 'Greg is a rhino' or both then Bernhard is a frog. Chances are about even that if either 'Brian is a lion' or 'Julius is a swan' but not both then Mary picked up the milk.
hypothesis: It is highly likely that 'Greg is a rhino and Lily is a swan'.
valid_hypothesis: It is highly unlikely that 'Greg is a rhino and Lily is a swan'.
invalid_hypothesis: It is highly likely that 'Greg is a rhino and Lily is a swan'.
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
    0.1::factA.
    0.1::factB.
    1.0::factC.
    %hop1
    0.6::factX:-and(factB,factC).
    0.75::factY:-or(factB,factC).
    0.5::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-and(factC,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a rhino and Lily is a swan'.