context: It is probably the case that Gertrude is a sheep. It is probably the case that Julius is a frog. We doubt that Mary went to the office. It is probable that if 'Julius is a frog and Mary went to the office' then Winona is a wolf. There is a very good chance that if either 'Gertrude is a sheep' or 'Mary went to the office' but not both then Bernhard is green. Chances are slight that if 'Mary went to the office' or 'Gertrude is a sheep' or both then Brian is gray.
hypothesis: There is a very good chance that 'Gertrude is a sheep and Mary went to the office'.
valid_hypothesis: It is improbable that 'Gertrude is a sheep and Mary went to the office'.
invalid_hypothesis: There is a very good chance that 'Gertrude is a sheep and Mary 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
    0.7::factA.
    0.7::factB.
    0.2::factC.
    %hop1
    0.7::factX:-and(factB,factC).
    0.8::factY:-xor(factA,factC).
    0.1::factZ:-or(factC,factA).
  
    %hop2
    conclusion:-and(factA,factC).
  
    query(conclusion).
    
hypothesis_assertion: 'Gertrude is a sheep and Mary went to the office'.