There is almost no chance that Brian is yellow. It is impossible that Greg is a swan. It is almost certain that Julius is a frog. It is probably not the case that if 'Greg is a swan and Brian is yellow' then Fred is in the cinema. It is probably the case that if either 'Julius is a frog' or 'Greg is a swan' but not both then John got the apple. We doubt that if 'Greg is a swan and Julius is a frog' then Jessica is a mouse.
It is certain that 'Julius is a frog and Brian is yellow'.
There is almost no chance that 'Julius is a frog and Brian is yellow'.
It is certain that 'Julius is a frog and Brian is yellow'.

  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.
  0.0::factB.
  0.95::factC.
  %hop1
  0.25::factX:-and(factB,factA).
  0.7::factY:-xor(factC,factB).
  0.2::factZ:-and(factB,factC).

  %hop2
  conclusion:-and(factC,factA).

  query(conclusion).
  
'Julius is a frog and Brian is yellow'.