It is highly likely that Mary discarded the apple. It is unlikely that Sandra got the football. We doubt that Brian is a swan. It is highly likely that if either 'Mary discarded the apple' or 'Sandra got the football' but not both then Lily is a lion. It is probably not the case that if 'Mary discarded the apple and Sandra got the football' then Emily is a wolf. It is highly unlikely that if either 'Brian is a swan' or 'Sandra got the football' but not both then John moved to the garden.
It is likely that either 'Emily is a wolf' or 'Lily is a lion' but not both.
It is likely that either 'Emily is a wolf' or 'Lily is a lion' but not both.
It is probably not the case that either 'Emily is a wolf' or 'Lily is a lion' but not 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
  0.9::factA.
  0.2::factB.
  0.2::factC.
  %hop1
  0.9::factX:-xor(factA,factB).
  0.25::factY:-and(factA,factB).
  0.05::factZ:-xor(factC,factB).

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

  query(conclusion).
  
Either 'Emily is a wolf' or 'Lily is a lion' but not both.