context: It is probably the case that Julius is a lion. There is little chance that Bill left the football. It is improbable that Greg is a swan.
hypothesis: It is highly unlikely that 'Greg is a swan and Julius is a lion'.
valid_hypothesis: It is highly unlikely that 'Greg is a swan and Julius is a lion'.
invalid_hypothesis: There is a better than even chance that 'Greg is a swan and Julius 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
    0.7::factA.
    0.1::factB.
    0.1::factC.
    
  
    %hop2
    conclusion:-and(factC,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a swan and Julius is a lion'.