There is a very good chance that Sandra got the milk. It is likely that John dropped the apple. There is a better than even chance that Bernhard is yellow. It is probably the case that if 'Bernhard is yellow and John dropped the apple' then Lily is a lion. It is probable that if 'John dropped the apple' or 'Bernhard is yellow' or both then Brian is a frog. We believe that if either 'Sandra got the milk' or 'Bernhard is yellow' but not both then Mary moved to the garden.
It is improbable that 'Bernhard is yellow' or 'Lily is a lion' or both.
There is a better than even chance that 'Bernhard is yellow' or 'Lily is a lion' or both.
It is improbable that 'Bernhard is yellow' or 'Lily is a lion' or both.

  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
  0.8::factA.
  0.7::factB.
  0.6::factC.
  %hop1
  0.7::factX:-and(factC,factB).
  0.7::factY:-or(factB,factC).
  0.75::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Bernhard is yellow' or 'Lily is a lion' or both.