It is highly unlikely that Greg is a rhino. It is likely that Bill went to the garden. There is a very good chance that Gertrude is a wolf. There is almost no chance that if 'Gertrude is a wolf and Bill went to the garden' then Sumit is hungry. There is a very good chance that if 'Gertrude is a wolf' or 'Bill went to the garden' or both then John discarded the milk. There is a better than even chance that if either 'Greg is a rhino' or 'Gertrude is a wolf' but not both then Julius is a swan.
It is probable that either 'John discarded the milk' or 'Gertrude is a wolf' but not both.
It is probably not the case that either 'John discarded the milk' or 'Gertrude is a wolf' but not both.
It is probable that either 'John discarded the milk' or 'Gertrude 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
  0.05::factA.
  0.7::factB.
  0.8::factC.
  %hop1
  0.02::factX:-and(factC,factB).
  0.8::factY:-or(factC,factB).
  0.6::factZ:-xor(factA,factC).

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

  query(conclusion).
  
Either 'John discarded the milk' or 'Gertrude is a wolf' but not both.