context: There is almost no chance that John went to the office. There is a very good chance that Brian is a swan. It is probably the case that Gertrude is a mouse. Chances are about even that if either 'John went to the office' or 'Gertrude is a mouse' but not both then Greg is a lion. It is likely that if 'Gertrude is a mouse' or 'Brian is a swan' or both then Mary got the apple. There is a very good chance that if 'John went to the office and Gertrude is a mouse' then Daniel dropped the milk.
hypothesis: It is almost certain that 'Brian is a swan and John went to the office'.
valid_hypothesis: There is almost no chance that 'Brian is a swan and John went to the office'.
invalid_hypothesis: It is almost certain that 'Brian is a swan and John went to the office'.
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
    0.02::factA.
    0.8::factB.
    0.7::factC.
    %hop1
    0.5::factX:-xor(factA,factC).
    0.7::factY:-or(factC,factB).
    0.8::factZ:-and(factA,factC).
  
    %hop2
    conclusion:-and(factB,factA).
  
    query(conclusion).
    
hypothesis_assertion: 'Brian is a swan and John went to the office'.