context: It is probably the case that Greg is a lion. Chances are about even that Lily is a rhino. It is impossible that Gertrude is a mouse. There is little chance that if 'Greg is a lion and Lily is a rhino' then Daniel got the football. It is highly unlikely that if 'Greg is a lion and Gertrude is a mouse' then Bernhard is white. We believe that if either 'Gertrude is a mouse' or 'Greg is a lion' but not both then Jason is tired.
hypothesis: It is unlikely that either 'Daniel got the football' or 'Greg is a lion' but not both.
valid_hypothesis: It is probably the case that either 'Daniel got the football' or 'Greg is a lion' but not both.
invalid_hypothesis: It is unlikely that either 'Daniel got the football' or 'Greg is a lion' 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.
    0.5::factB.
    0.0::factC.
    %hop1
    0.1::factX:-and(factA,factB).
    0.05::factY:-and(factA,factC).
    0.75::factZ:-xor(factC,factA).
  
    %hop2
    conclusion:-xor(factX,factA).
  
    query(conclusion).
    
hypothesis_assertion: Either 'Daniel got the football' or 'Greg is a lion' but not both.