context: There is little chance that John grabbed the apple. We believe that Mary left the football. It is highly unlikely that Bernhard is a swan. It is probably not the case that if either 'Mary left the football' or 'John grabbed the apple' but not both then Julius is a frog. We doubt that if either 'Mary left the football' or 'Bernhard is a swan' but not both then Lily is white. It is unlikely that if 'John grabbed the apple and Mary left the football' then Sandra got the milk.
hypothesis: It is probably the case that 'Sandra got the milk and Julius is a frog'.
valid_hypothesis: It is impossible that 'Sandra got the milk and Julius is a frog'.
invalid_hypothesis: It is probably the case that 'Sandra got the milk and Julius is a frog'.
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
    0.1::factA.
    0.75::factB.
    0.05::factC.
    %hop1
    0.25::factX:-xor(factB,factA).
    0.2::factY:-xor(factB,factC).
    0.2::factZ:-and(factA,factB).
  
    %hop2
    conclusion:-and(factZ,factX).
  
    query(conclusion).
    
hypothesis_assertion: 'Sandra got the milk and Julius is a frog'.