It is highly likely that Greg is a lion. There is a very good chance that Emily is a sheep. There is a very good chance that Winona is a wolf. It is likely that if 'Greg is a lion and Emily is a sheep' then Julius is a swan. Chances are slight that if either 'Winona is a wolf' or 'Emily is a sheep' but not both then Sandra got the football. It is impossible that if 'Winona is a wolf and Greg is a lion' then John picked up the apple.
It is likely that either 'Greg is a lion' or 'Winona is a wolf' but not both.
It is probably not the case that either 'Greg is a lion' or 'Winona is a wolf' but not both.
It is likely that either 'Greg is a lion' or 'Winona is a wolf' 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.
  0.8::factB.
  0.8::factC.
  %hop1
  0.7::factX:-and(factA,factB).
  0.1::factY:-xor(factC,factB).
  0.0::factZ:-and(factC,factA).

  %hop2
  conclusion:-xor(factA,factC).

  query(conclusion).
  
Either 'Greg is a lion' or 'Winona is a wolf' but not both.