context: Chances are slight that Greg is gray. There is a better than even chance that Emily is a sheep. It is highly likely that Mary went to the kitchen. It is likely that if 'Emily is a sheep' or 'Mary went to the kitchen' or both then Fred is in the cinema. It is impossible that if either 'Greg is gray' or 'Emily is a sheep' but not both then Lily is a swan. Chances are about even that if either 'Emily is a sheep' or 'Greg is gray' but not both then Bernhard is a lion.
hypothesis: It is probably the case that 'Bernhard is a lion and Greg is gray'.
valid_hypothesis: There is almost no chance that 'Bernhard is a lion and Greg is gray'.
invalid_hypothesis: It is probably the case that 'Bernhard is a lion and Greg is gray'.
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
    0.1::factA.
    0.6::factB.
    0.9::factC.
    %hop1
    0.7::factX:-or(factB,factC).
    0.0::factY:-xor(factA,factB).
    0.5::factZ:-xor(factB,factA).
  
    %hop2
    conclusion:-and(factZ,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is a lion and Greg is gray'.