context: There is a very good chance that Emily is a sheep. It is probable that John went to the kitchen. It is highly likely that Bernhard is yellow. There is almost no chance that if 'John went to the kitchen' or 'Emily is a sheep' or both then Daniel got the football. We believe that if 'Bernhard is yellow and John went to the kitchen' then Julius is a swan. Chances are about even that if either 'Emily is a sheep' or 'John went to the kitchen' but not both then Mary picked up the milk.
hypothesis: It is highly unlikely that either 'Julius is a swan' or 'Emily is a sheep' but not both.
valid_hypothesis: Chances are about even that either 'Julius is a swan' or 'Emily is a sheep' but not both.
invalid_hypothesis: It is highly unlikely that either 'Julius is a swan' or 'Emily is a sheep' 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
    0.8::factA.
    0.7::factB.
    0.9::factC.
    %hop1
    0.02::factX:-or(factB,factA).
    0.75::factY:-and(factC,factB).
    0.5::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-xor(factY,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Julius is a swan' or 'Emily is a sheep' but not both.