context: It is certain that Mary dropped the milk. It is highly unlikely that John went to the garden. It is probably the case that Bernhard is a frog. It is almost certain that if 'John went to the garden and Mary dropped the milk' then Greg is a swan. It is improbable that if 'John went to the garden and Mary dropped the milk' then Julius is a rhino. It is probable that if 'Bernhard is a frog' or 'John went to the garden' or both then Yann is tired.
hypothesis: It is certain that 'Greg is a swan' or 'John went to the garden' or both.
valid_hypothesis: It is highly unlikely that 'Greg is a swan' or 'John went to the garden' or both.
invalid_hypothesis: It is certain that 'Greg is a swan' or 'John went to the garden' 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
    1.0::factA.
    0.05::factB.
    0.7::factC.
    %hop1
    0.95::factX:-and(factB,factA).
    0.1::factY:-and(factB,factA).
    0.7::factZ:-or(factC,factB).
  
    %hop2
    conclusion:-or(factX,factB).
  
    query(conclusion).
    
hypothesis_assertion: 'Greg is a swan' or 'John went to the garden' or both.