Chances are about even that Emily is a mouse. Chances are slight that Jeff went to the bedroom. It is highly unlikely that Brian is green. It is highly likely that if 'Emily is a mouse' or 'Brian is green' or both then Julius is a lion. It is improbable that if 'Emily is a mouse' or 'Brian is green' or both then John discarded the milk. There is a better than even chance that if either 'Emily is a mouse' or 'Jeff went to the bedroom' but not both then Lily is a rhino.
It is probably the case that either 'Lily is a rhino' or 'Brian is green' but not both.
It is probably not the case that either 'Lily is a rhino' or 'Brian is green' but not both.
It is probably the case that either 'Lily is a rhino' or 'Brian is green' 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
  0.5::factA.
  0.1::factB.
  0.05::factC.
  %hop1
  0.9::factX:-or(factA,factC).
  0.1::factY:-or(factA,factC).
  0.6::factZ:-xor(factA,factB).

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

  query(conclusion).
  
Either 'Lily is a rhino' or 'Brian is green' but not both.