Chances are slight that Emily is a wolf. We believe that Bernhard is a swan. It is highly likely that Sandra dropped the milk. It is likely that if either 'Emily is a wolf' or 'Bernhard is a swan' but not both then John left the football. It is certain that if 'Bernhard is a swan and Sandra dropped the milk' then Jason is tired. It is probably not the case that if either 'Bernhard is a swan' or 'Sandra dropped the milk' but not both then Jessica is a cat.
There is a better than even chance that 'Emily is a wolf' or 'John left the football' or both.
There is a better than even chance that 'Emily is a wolf' or 'John left the football' or both.
Chances are slight that 'Emily is a wolf' or 'John left the football' 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
  0.1::factA.
  0.75::factB.
  0.9::factC.
  %hop1
  0.7::factX:-xor(factA,factB).
  1.0::factY:-and(factB,factC).
  0.25::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Emily is a wolf' or 'John left the football' or both.