context: It is highly likely that Bernhard is a rhino. It is impossible that Brian is a lion. It is highly unlikely that Greg is a swan. It is impossible that if 'Brian is a lion' or 'Bernhard is a rhino' or both then Bill moved to the office. It is almost certain that if either 'Bernhard is a rhino' or 'Brian is a lion' but not both then John grabbed the apple. It is highly unlikely that if either 'Bernhard is a rhino' or 'Greg is a swan' but not both then Mary went to the bedroom.
hypothesis: It is highly unlikely that 'Brian is a lion' or 'Greg is a swan' or both.
valid_hypothesis: It is highly unlikely that 'Brian is a lion' or 'Greg is a swan' or both.
invalid_hypothesis: It is likely that 'Brian is a lion' 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
    0.9::factA.
    0.0::factB.
    0.05::factC.
    %hop1
    0.0::factX:-or(factB,factA).
    0.95::factY:-xor(factA,factB).
    0.05::factZ:-xor(factA,factC).
  
    %hop2
    conclusion:-or(factB,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a lion' or 'Greg is a swan' or both.