context: It is likely that Julius is a swan. Chances are slight that Mary moved to the office. It is probable that Greg is a frog. It is highly likely that if 'Julius is a swan and Mary moved to the office' then Brian is a rhino. It is highly unlikely that if 'Greg is a frog and Julius is a swan' then Bernhard is yellow. It is almost certain that if either 'Mary moved to the office' or 'Julius is a swan' but not both then Fred left the apple.
hypothesis: It is impossible that 'Bernhard is yellow' or 'Fred left the apple' or both.
valid_hypothesis: There is a better than even chance that 'Bernhard is yellow' or 'Fred left the apple' or both.
invalid_hypothesis: It is impossible that 'Bernhard is yellow' or 'Fred left 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.
    0.1::factB.
    0.7::factC.
    %hop1
    0.9::factX:-and(factA,factB).
    0.05::factY:-and(factC,factA).
    0.95::factZ:-xor(factB,factA).
  
    %hop2
    conclusion:-or(factY,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Bernhard is yellow' or 'Fred left the apple' or both.