context: It is impossible that Julius is a swan. It is certain that Gertrude is a sheep. Chances are slight that Mary moved to the office. It is certain that if either 'Gertrude is a sheep' or 'Mary moved to the office' but not both then Fred went to the garden. Chances are about even that if 'Gertrude is a sheep and Mary moved to the office' then Jason is tired. It is highly unlikely that if either 'Julius is a swan' or 'Gertrude is a sheep' but not both then Greg is a rhino.
hypothesis: It is likely that 'Mary moved to the office' or 'Greg is a rhino' or both.
valid_hypothesis: Chances are slight that 'Mary moved to the office' or 'Greg is a rhino' or both.
invalid_hypothesis: It is likely that 'Mary moved to the office' or 'Greg is a rhino' 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
    0.0::factA.
    1.0::factB.
    0.1::factC.
    %hop1
    1.0::factX:-xor(factB,factC).
    0.5::factY:-and(factB,factC).
    0.05::factZ:-xor(factA,factB).
  
    %hop2
    conclusion:-or(factC,factZ).
  
    query(conclusion).
    
hypothesis_assertion: 'Mary moved to the office' or 'Greg is a rhino' or both.