context: It is impossible that John put down the milk. It is probably the case that Mary left the football. There is a very good chance that Bernhard is gray. It is likely that if either 'Bernhard is gray' or 'Mary left the football' but not both then Greg is a frog. It is probably the case that if 'Bernhard is gray and Mary left the football' then Brian is a rhino. There is little chance that if either 'Mary left the football' or 'John put down the milk' but not both then Lily is a lion.
hypothesis: It is impossible that 'Greg is a frog and John put down the milk'.
valid_hypothesis: It is impossible that 'Greg is a frog and John put down the milk'.
invalid_hypothesis: It is likely that 'Greg is a frog and John put down 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
    0.0::factA.
    0.7::factB.
    0.8::factC.
    %hop1
    0.7::factX:-xor(factC,factB).
    0.7::factY:-and(factC,factB).
    0.1::factZ:-xor(factB,factA).
  
    %hop2
    conclusion:-and(factX,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a frog and John put down the milk'.