It is probable that Lily is green. It is improbable that Bernhard is gray. We believe that Brian is yellow. Chances are about even that if either 'Brian is yellow' or 'Lily is green' but not both then John moved to the office. Chances are slight that if 'Brian is yellow' or 'Lily is green' or both then Mary left the apple. There is a very good chance that if either 'Bernhard is gray' or 'Lily is green' but not both then Sandra took the football.
There is almost no chance that 'Brian is yellow' or 'John moved to the office' or both.
There is a very good chance that 'Brian is yellow' or 'John moved to the office' or both.
There is almost no chance that 'Brian is yellow' or 'John moved to the office' or 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
  0.7::factA.
  0.1::factB.
  0.75::factC.
  %hop1
  0.5::factX:-xor(factC,factA).
  0.1::factY:-or(factC,factA).
  0.8::factZ:-xor(factB,factA).

  %hop2
  conclusion:-or(factC,factX).

  query(conclusion).
  
'Brian is yellow' or 'John moved to the office' or both.