context: It is unlikely that Emily is a sheep. We believe that Bernhard is white. It is impossible that Daniel left the apple. It is probably the case that if either 'Bernhard is white' or 'Emily is a sheep' but not both then John put down the milk. Chances are about even that if either 'Bernhard is white' or 'Emily is a sheep' but not both then Julius is a swan. We believe that if 'Daniel left the apple and Bernhard is white' then Jeff went to the garden.
hypothesis: It is highly unlikely that 'Bernhard is white' or 'Emily is a sheep' or both.
valid_hypothesis: There is a very good chance that 'Bernhard is white' or 'Emily is a sheep' or both.
invalid_hypothesis: It is highly unlikely that 'Bernhard is white' or 'Emily is a sheep' 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
    0.2::factA.
    0.75::factB.
    0.0::factC.
    %hop1
    0.7::factX:-xor(factB,factA).
    0.5::factY:-xor(factB,factA).
    0.75::factZ:-and(factC,factB).
  
    %hop2
    conclusion:-or(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is white' or 'Emily is a sheep' or both.