context: We believe that Lily is a rhino. It is probably not the case that John moved to the garden. We doubt that Julius is a swan. It is impossible that if 'Lily is a rhino' or 'John moved to the garden' or both then Bernhard is green. We believe that if 'Julius is a swan' or 'Lily is a rhino' or both then Mary picked up the apple. Chances are slight that if 'Lily is a rhino and John moved to the garden' then Greg is white.
hypothesis: It is likely that either 'Lily is a rhino' or 'Mary picked up the apple' but not both.
valid_hypothesis: We doubt that either 'Lily is a rhino' or 'Mary picked up the apple' but not both.
invalid_hypothesis: It is likely that either 'Lily is a rhino' or 'Mary picked up the apple' but not 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
    0.75::factA.
    0.25::factB.
    0.2::factC.
    %hop1
    0.0::factX:-or(factA,factB).
    0.75::factY:-or(factC,factA).
    0.1::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-xor(factA,factY).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Lily is a rhino' or 'Mary picked up the apple' but not both.