context: It is likely that Julius is yellow. Chances are about even that Lily is a swan. There is little chance that Greg is a lion. Chances are slight that if either 'Lily is a swan' or 'Greg is a lion' but not both then Sumit is thirsty. Chances are slight that if either 'Julius is yellow' or 'Lily is a swan' but not both then Sandra dropped the apple. It is likely that if 'Julius is yellow and Lily is a swan' then John went to the kitchen.
hypothesis: It is improbable that 'Sumit is thirsty' or 'Sandra dropped the apple' or both.
valid_hypothesis: It is improbable that 'Sumit is thirsty' or 'Sandra dropped the apple' or both.
invalid_hypothesis: It is almost certain that 'Sumit is thirsty' or 'Sandra dropped the apple' or 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.
    0.1::factC.
    %hop1
    0.1::factX:-xor(factB,factC).
    0.1::factY:-xor(factA,factB).
    0.7::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-or(factX,factY).
  
    query(conclusion).
    
hypothesis_assertion: 'Sumit is thirsty' or 'Sandra dropped the apple' or both.