There is a better than even chance that Gertrude is a sheep. It is highly unlikely that Julius is a rhino. We believe that Mary got the football. Chances are about even that if 'Julius is a rhino and Mary got the football' then Sandra left the apple. It is impossible that if 'Mary got the football and Gertrude is a sheep' then Brian is white. It is highly likely that if either 'Julius is a rhino' or 'Mary got the football' but not both then Bernhard is green.
It is highly unlikely that either 'Gertrude is a sheep' or 'Julius is a rhino' but not both.
There is a better than even chance that either 'Gertrude is a sheep' or 'Julius is a rhino' but not both.
It is highly unlikely that either 'Gertrude is a sheep' or 'Julius 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
  0.6::factA.
  0.05::factB.
  0.75::factC.
  %hop1
  0.5::factX:-and(factB,factC).
  0.0::factY:-and(factC,factA).
  0.9::factZ:-xor(factB,factC).

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

  query(conclusion).
  
Either 'Gertrude is a sheep' or 'Julius is a rhino' but not both.