There is a very good chance that Bernhard is green. It is probably not the case that John put down the apple. It is impossible that Brian is yellow. It is probable that if 'Brian is yellow and John put down the apple' then Mary discarded the milk. It is highly likely that if 'Brian is yellow' or 'Bernhard is green' or both then Sandra left the football. It is probable that if 'Bernhard is green' or 'Brian is yellow' or both then Bill went to the bedroom.
Chances are about even that either 'John put down the apple' or 'Bill went to the bedroom' but not both.
Chances are about even that either 'John put down the apple' or 'Bill went to the bedroom' but not both.
There is almost no chance that either 'John put down the apple' or 'Bill went to the bedroom' 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
  0.8::factA.
  0.25::factB.
  0.0::factC.
  %hop1
  0.7::factX:-and(factC,factB).
  0.9::factY:-or(factC,factA).
  0.7::factZ:-or(factA,factC).

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

  query(conclusion).
  
Either 'John put down the apple' or 'Bill went to the bedroom' but not both.