context: It is certain that Sandra took the milk. There is a very good chance that Mary moved to the office. Chances are about even that Jessica is a cat. We doubt that if either 'Mary moved to the office' or 'Jessica is a cat' but not both then John went to the garden. It is highly unlikely that if 'Mary moved to the office' or 'Jessica is a cat' or both then Lily is a rhino. It is highly likely that if 'Jessica is a cat and Sandra took the milk' then Greg is a swan.
hypothesis: It is improbable that 'John went to the garden' or 'Jessica is a cat' or both.
valid_hypothesis: There is a better than even chance that 'John went to the garden' or 'Jessica is a cat' or both.
invalid_hypothesis: It is improbable that 'John went to the garden' or 'Jessica is a cat' 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
    1.0::factA.
    0.8::factB.
    0.5::factC.
    %hop1
    0.2::factX:-xor(factB,factC).
    0.05::factY:-or(factB,factC).
    0.9::factZ:-and(factC,factA).
  
    %hop2
    conclusion:-or(factX,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'John went to the garden' or 'Jessica is a cat' or both.