It is probably not the case that Greg is green. There is little chance that Winona is a cat. It is highly likely that Brian is a rhino. There is a very good chance that if 'Winona is a cat and Greg is green' then Mary went to the garden. It is highly likely that if 'Winona is a cat and Brian is a rhino' then Julius is a swan. It is almost certain that if 'Greg is green and Brian is a rhino' then John moved to the office.
It is likely that either 'Julius is a swan' or 'Winona is a cat' but not both.
There is almost no chance that either 'Julius is a swan' or 'Winona is a cat' but not both.
It is likely that either 'Julius is a swan' or 'Winona is a cat' 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
  0.25::factA.
  0.1::factB.
  0.9::factC.
  %hop1
  0.8::factX:-and(factB,factA).
  0.9::factY:-and(factB,factC).
  0.95::factZ:-and(factA,factC).

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

  query(conclusion).
  
Either 'Julius is a swan' or 'Winona is a cat' but not both.