context: It is probably not the case that Julius is a frog. It is highly unlikely that Mary left the football. It is certain that John went to the office. There is a better than even chance that if 'Mary left the football and John went to the office' then Lily is green. There is a very good chance that if 'Julius is a frog and Mary left the football' then Greg is white. There is a better than even chance that if 'John went to the office and Julius is a frog' then Winona is a sheep.
hypothesis: It is almost certain that either 'John went to the office' or 'Mary left the football' but not both.
valid_hypothesis: It is almost certain that either 'John went to the office' or 'Mary left the football' but not both.
invalid_hypothesis: There is almost no chance that either 'John went to the office' or 'Mary left the football' 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
    0.25::factA.
    0.05::factB.
    1.0::factC.
    %hop1
    0.6::factX:-and(factB,factC).
    0.8::factY:-and(factA,factB).
    0.6::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-xor(factC,factB).
  
    query(conclusion).
    
hypothesis_assertion: Either 'John went to the office' or 'Mary left the football' but not both.