context: It is impossible that Mary went to the kitchen. It is unlikely that Julius is a rhino. It is impossible that Greg is a swan. It is unlikely that if 'Greg is a swan' or 'Julius is a rhino' or both then Sandra dropped the milk. It is impossible that if 'Greg is a swan' or 'Mary went to the kitchen' or both then Brian is green. It is almost certain that if either 'Greg is a swan' or 'Mary went to the kitchen' but not both then Bernhard is gray.
hypothesis: It is impossible that 'Mary went to the kitchen' or 'Greg is a swan' or both.
valid_hypothesis: It is impossible that 'Mary went to the kitchen' or 'Greg is a swan' or both.
invalid_hypothesis: It is probably the case that 'Mary went to the kitchen' or 'Greg is a swan' or both.
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.
    0.2::factB.
    0.0::factC.
    %hop1
    0.2::factX:-or(factC,factB).
    0.0::factY:-or(factC,factA).
    0.95::factZ:-xor(factC,factA).
  
    %hop2
    conclusion:-or(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Mary went to the kitchen' or 'Greg is a swan' or both.