It is likely that Lily is white. There is a better than even chance that John took the football. There is a better than even chance that Mary went to the office. Chances are slight that if either 'Lily is white' or 'Mary went to the office' but not both then Sandra dropped the milk. Chances are about even that if 'John took the football' or 'Lily is white' or both then Bernhard is a swan. It is unlikely that if either 'John took the football' or 'Lily is white' but not both then Yann is hungry.
It is likely that 'Lily is white' or 'Sandra dropped the milk' or both.
It is likely that 'Lily is white' or 'Sandra dropped the milk' or both.
There is almost no chance that 'Lily is white' or 'Sandra dropped the milk' 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
  0.7::factA.
  0.6::factB.
  0.6::factC.
  %hop1
  0.1::factX:-xor(factA,factC).
  0.5::factY:-or(factB,factA).
  0.2::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Lily is white' or 'Sandra dropped the milk' or both.