context: It is probable that Brian is a frog. It is probable that John left the football. It is likely that Greg is yellow. It is almost certain that if 'John left the football and Greg is yellow' then Lily is a lion. There is a very good chance that if 'Brian is a frog and John left the football' then Bernhard is green. There is a very good chance that if either 'Greg is yellow' or 'Brian is a frog' but not both then Mary took the milk.
hypothesis: It is probably the case that 'Greg is yellow and Mary took the milk'.
valid_hypothesis: We doubt that 'Greg is yellow and Mary took the milk'.
invalid_hypothesis: It is probably the case that 'Greg is yellow and Mary took 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
    0.7::factA.
    0.7::factB.
    0.7::factC.
    %hop1
    0.95::factX:-and(factB,factC).
    0.8::factY:-and(factA,factB).
    0.8::factZ:-xor(factC,factA).
  
    %hop2
    conclusion:-and(factC,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is yellow and Mary took the milk'.