context: It is probable that Mary is in the school. It is probably the case that Bill moved to the office. It is probable that Greg is a swan. There is little chance that if either 'Mary is in the school' or 'Greg is a swan' but not both then Emily is a sheep. Chances are about even that if 'Bill moved to the office and Greg is a swan' then Jason is thirsty. It is probable that if 'Mary is in the school' or 'Bill moved to the office' or both then Julius is white.
hypothesis: There is a better than even chance that either 'Emily is a sheep' or 'Julius is white' but not both.
valid_hypothesis: There is a better than even chance that either 'Emily is a sheep' or 'Julius is white' but not both.
invalid_hypothesis: There is little chance that either 'Emily is a sheep' or 'Julius is white' 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
    0.7::factA.
    0.7::factB.
    0.7::factC.
    %hop1
    0.1::factX:-xor(factA,factC).
    0.5::factY:-and(factB,factC).
    0.7::factZ:-or(factA,factB).
  
    %hop2
    conclusion:-xor(factX,factZ).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Emily is a sheep' or 'Julius is white' but not both.