context: It is probably the case that Bernhard is green. It is probably not the case that Jason is tired. It is improbable that Julius is white. It is likely that if either 'Bernhard is green' or 'Jason is tired' but not both then Brian is a frog. It is probably not the case that if 'Julius is white' or 'Jason is tired' or both then John dropped the apple. It is highly unlikely that if 'Jason is tired and Bernhard is green' then Sandra got the milk.
hypothesis: Chances are about even that 'Brian is a frog' or 'Sandra got the milk' or both.
valid_hypothesis: Chances are about even that 'Brian is a frog' or 'Sandra got the milk' or both.
invalid_hypothesis: It is certain that 'Brian is a frog' or 'Sandra got the milk' 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.
    0.25::factB.
    0.1::factC.
    %hop1
    0.7::factX:-xor(factA,factB).
    0.25::factY:-or(factC,factB).
    0.05::factZ:-and(factB,factA).
  
    %hop2
    conclusion:-or(factX,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a frog' or 'Sandra got the milk' or both.