context: It is probable that Lily is white. It is probable that Emily is a mouse. It is impossible that Mary left the football. There is a better than even chance that if either 'Lily is white' or 'Mary left the football' but not both then Julius is a frog. It is certain that if either 'Lily is white' or 'Emily is a mouse' but not both then John went to the garden. It is highly unlikely that if either 'Lily is white' or 'Emily is a mouse' but not both then Brian is a swan.
hypothesis: There is almost no chance that 'Brian is a swan and Lily is white'.
valid_hypothesis: There is almost no chance that 'Brian is a swan and Lily is white'.
invalid_hypothesis: It is highly likely that 'Brian is a swan and Lily is white'.
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.
    0.7::factB.
    0.0::factC.
    %hop1
    0.6::factX:-xor(factA,factC).
    1.0::factY:-xor(factA,factB).
    0.05::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-and(factZ,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a swan and Lily is white'.