There is almost no chance that Brian is a swan. It is almost certain that Jason is tired. It is likely that Greg is a rhino. There is almost no chance that if 'Greg is a rhino and Jason is tired' then Sandra took the milk. It is highly likely that if 'Greg is a rhino and Jason is tired' then Fred put down the apple. There is almost no chance that if either 'Brian is a swan' or 'Greg is a rhino' but not both then Bernhard is a lion.
It is likely that either 'Greg is a rhino' or 'Brian is a swan' but not both.
It is likely that either 'Greg is a rhino' or 'Brian is a swan' but not both.
It is probably not the case that either 'Greg is a rhino' or 'Brian is a swan' 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
  0.02::factA.
  0.95::factB.
  0.7::factC.
  %hop1
  0.02::factX:-and(factC,factB).
  0.9::factY:-and(factC,factB).
  0.02::factZ:-xor(factA,factC).

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

  query(conclusion).
  
Either 'Greg is a rhino' or 'Brian is a swan' but not both.