context: It is probably the case that Lily is a frog. It is improbable that Mary went to the office. There is almost no chance that Bernhard is a rhino. We believe that if 'Lily is a frog and Bernhard is a rhino' then Brian is white. We doubt that if 'Lily is a frog and Bernhard is a rhino' then Greg is a swan. There is a better than even chance that if 'Mary went to the office and Bernhard is a rhino' then Sandra put down the milk.
hypothesis: There is almost no chance that 'Bernhard is a rhino' or 'Brian is white' or both.
valid_hypothesis: There is almost no chance that 'Bernhard is a rhino' or 'Brian is white' or both.
invalid_hypothesis: It is certain that 'Bernhard is a rhino' or 'Brian is white' 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.
    0.1::factB.
    0.02::factC.
    %hop1
    0.75::factX:-and(factA,factC).
    0.2::factY:-and(factA,factC).
    0.6::factZ:-and(factB,factC).
  
    %hop2
    conclusion:-or(factC,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is a rhino' or 'Brian is white' or both.