context: There is a better than even chance that Greg is yellow. There is a better than even chance that John moved to the office. It is impossible that Jeff discarded the milk. It is probably the case that if either 'Greg is yellow' or 'Jeff discarded the milk' but not both then Mary got the milk. It is highly likely that if either 'Jeff discarded the milk' or 'Greg is yellow' but not both then Sandra is in the kitchen. Chances are about even that if 'Jeff discarded the milk and John moved to the office' then Brian is white.
hypothesis: It is impossible that 'Greg is yellow and Jeff discarded the milk'.
valid_hypothesis: It is impossible that 'Greg is yellow and Jeff discarded the milk'.
invalid_hypothesis: There is a better than even chance that 'Greg is yellow and Jeff discarded the milk'.
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
    0.6::factA.
    0.6::factB.
    0.0::factC.
    %hop1
    0.7::factX:-xor(factA,factC).
    0.9::factY:-xor(factC,factA).
    0.5::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-and(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is yellow and Jeff discarded the milk'.