context: It is probable that Greg is a lion. There is a very good chance that Sandra grabbed the milk. It is probable that Julius is a swan. It is almost certain that if either 'Sandra grabbed the milk' or 'Julius is a swan' but not both then Lily is a frog. There is little chance that if 'Julius is a swan and Greg is a lion' then Mary went to the office. There is almost no chance that if either 'Greg is a lion' or 'Sandra grabbed the milk' but not both then Bernhard is yellow.
hypothesis: It is impossible that 'Bernhard is yellow and Mary went to the office'.
valid_hypothesis: It is impossible that 'Bernhard is yellow and Mary went to the office'.
invalid_hypothesis: There is a better than even chance that 'Bernhard is yellow and Mary went to the office'.
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.
    0.8::factB.
    0.7::factC.
    %hop1
    0.95::factX:-xor(factB,factC).
    0.1::factY:-and(factC,factA).
    0.02::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-and(factZ,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is yellow and Mary went to the office'.