Chances are about even that Mary dropped the milk. It is probable that John took the football. It is probable that Antoine is thirsty. There is a very good chance that if either 'Antoine is thirsty' or 'John took the football' but not both then Fred moved to the office. There is a better than even chance that if either 'Mary dropped the milk' or 'John took the football' but not both then Lily is a lion. It is certain that if 'Antoine is thirsty' or 'Mary dropped the milk' or both then Brian is a swan.
It is certain that 'Lily is a lion' or 'Fred moved to the office' or both.
Chances are about even that 'Lily is a lion' or 'Fred moved to the office' or both.
It is certain that 'Lily is a lion' or 'Fred moved to the office' 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
  0.5::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  0.8::factX:-xor(factC,factB).
  0.6::factY:-xor(factA,factB).
  1.0::factZ:-or(factC,factA).

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

  query(conclusion).
  
'Lily is a lion' or 'Fred moved to the office' or both.