There is a better than even chance that Lily is gray. Chances are about even that Bernhard is a frog. There is little chance that Greg is a frog. It is unlikely that if either 'Lily is gray' or 'Greg is a frog' but not both then Brian is a swan. We doubt that if either 'Lily is gray' or 'Greg is a frog' but not both then Julius is yellow. There is a better than even chance that if either 'Greg is a frog' or 'Lily is gray' but not both then Mary went to the garden.
It is certain that 'Greg is a frog and Brian is a swan'.
It is impossible that 'Greg is a frog and Brian is a swan'.
It is certain that 'Greg is a frog and Brian is a swan'.

  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
  0.6::factA.
  0.5::factB.
  0.1::factC.
  %hop1
  0.2::factX:-xor(factA,factC).
  0.2::factY:-xor(factA,factC).
  0.6::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Greg is a frog and Brian is a swan'.