It is impossible that Sumit is tired. There is a very good chance that Jeff moved to the office. We believe that Lily is green. We believe that if 'Lily is green' or 'Jeff moved to the office' or both then Bernhard is green. Chances are slight that if 'Lily is green and Jeff moved to the office' then Sandra left the milk. It is probable that if 'Jeff moved to the office' or 'Sumit is tired' or both then Brian is white.
Chances are about even that either 'Lily is green' or 'Brian is white' but not both.
Chances are about even that either 'Lily is green' or 'Brian is white' but not both.
It is impossible that either 'Lily is green' or 'Brian is white' 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.
  0.8::factB.
  0.75::factC.
  %hop1
  0.75::factX:-or(factC,factB).
  0.1::factY:-and(factC,factB).
  0.7::factZ:-or(factB,factA).

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

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