context: Chances are about even that Brian is a rhino. It is unlikely that Greg is white. There is a better than even chance that Julius is yellow. It is almost certain that if 'Brian is a rhino' or 'Julius is yellow' or both then Jeff left the apple. It is probable that if 'Brian is a rhino and Julius is yellow' then Mary got the apple. It is almost certain that if 'Brian is a rhino' or 'Greg is white' or both then John picked up the milk.
hypothesis: There is a very good chance that 'Jeff left the apple' or 'Greg is white' or both.
valid_hypothesis: There is a very good chance that 'Jeff left the apple' or 'Greg is white' or both.
invalid_hypothesis: It is impossible that 'Jeff left the apple' or 'Greg is white' 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
    0.5::factA.
    0.2::factB.
    0.6::factC.
    %hop1
    0.95::factX:-or(factA,factC).
    0.7::factY:-and(factA,factC).
    0.95::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-or(factX,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Jeff left the apple' or 'Greg is white' or both.