It is impossible that Fred went to the garden. There is little chance that Winona is a wolf. It is probably not the case that Bernhard is a rhino. It is probable that if either 'Fred went to the garden' or 'Bernhard is a rhino' but not both then Emily is a mouse. It is highly unlikely that if 'Winona is a wolf' or 'Bernhard is a rhino' or both then Lily is gray. It is probable that if 'Bernhard is a rhino and Fred went to the garden' then Greg is green.
It is certain that either 'Fred went to the garden' or 'Bernhard is a rhino' but not both.
It is probably not the case that either 'Fred went to the garden' or 'Bernhard is a rhino' but not both.
It is certain that either 'Fred went to the garden' or 'Bernhard is a rhino' 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
  0.0::factA.
  0.1::factB.
  0.25::factC.
  %hop1
  0.7::factX:-xor(factA,factC).
  0.05::factY:-or(factB,factC).
  0.7::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Fred went to the garden' or 'Bernhard is a rhino' but not both.