context: It is probable that Mary left the milk. We doubt that Bernhard is a lion. It is impossible that Sandra took the football. It is almost certain that if either 'Bernhard is a lion' or 'Mary left the milk' but not both then John went to the office. It is unlikely that if 'Mary left the milk and Bernhard is a lion' then Greg is gray. It is unlikely that if 'Mary left the milk' or 'Sandra took the football' or both then Jessica is a mouse.
hypothesis: It is highly unlikely that either 'Jessica is a mouse' or 'John went to the office' but not both.
valid_hypothesis: Chances are about even that either 'Jessica is a mouse' or 'John went to the office' but not both.
invalid_hypothesis: It is highly unlikely that either 'Jessica is a mouse' or 'John went to the office' 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.
    0.2::factB.
    0.0::factC.
    %hop1
    0.95::factX:-xor(factB,factA).
    0.2::factY:-and(factA,factB).
    0.2::factZ:-or(factA,factC).
  
    %hop2
    conclusion:-xor(factZ,factX).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Jessica is a mouse' or 'John went to the office' but not both.