It is unlikely that Brian is a frog. It is improbable that Greg is a swan. It is highly unlikely that John took the football. It is likely that if either 'John took the football' or 'Greg is a swan' but not both then Mary went to the garden. It is impossible that if 'John took the football' or 'Brian is a frog' or both then Lily is a rhino. It is highly unlikely that if either 'John took the football' or 'Brian is a frog' but not both then Bernhard is white.
It is likely that 'Bernhard is white and Greg is a swan'.
It is impossible that 'Bernhard is white and Greg is a swan'.
It is likely that 'Bernhard is white and Greg 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
  0.2::factA.
  0.1::factB.
  0.05::factC.
  %hop1
  0.7::factX:-xor(factC,factB).
  0.0::factY:-or(factC,factA).
  0.05::factZ:-xor(factC,factA).

  %hop2
  conclusion:-and(factZ,factB).

  query(conclusion).
  
'Bernhard is white and Greg is a swan'.