context: It is likely that Sandra dropped the milk. It is probably the case that Bernhard is a swan. There is almost no chance that Greg is yellow. It is almost certain that if 'Greg is yellow' or 'Bernhard is a swan' or both then Brian is a rhino. We believe that if 'Greg is yellow and Bernhard is a swan' then John went to the office. There is a better than even chance that if 'Bernhard is a swan' or 'Greg is yellow' or both then Mary put down the apple.
hypothesis: It is probably the case that 'Mary put down the apple' or 'Brian is a rhino' or both.
valid_hypothesis: It is probably the case that 'Mary put down the apple' or 'Brian is a rhino' or both.
invalid_hypothesis: It is highly unlikely that 'Mary put down the apple' or 'Brian is a rhino' 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
    0.7::factA.
    0.7::factB.
    0.02::factC.
    %hop1
    0.95::factX:-or(factC,factB).
    0.75::factY:-and(factC,factB).
    0.6::factZ:-or(factB,factC).
  
    %hop2
    conclusion:-or(factZ,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Mary put down the apple' or 'Brian is a rhino' or both.