Chances are about even that Daniel grabbed the apple. Chances are slight that Jason is tired. It is certain that Brian is white. It is highly likely that if either 'Brian is white' or 'Jason is tired' but not both then Sandra left the milk. There is almost no chance that if either 'Brian is white' or 'Jason is tired' but not both then John went to the office. We doubt that if either 'Brian is white' or 'Daniel grabbed the apple' but not both then Mary picked up the milk.
There is a better than even chance that 'Jason is tired' or 'Daniel grabbed the apple' or both.
There is a better than even chance that 'Jason is tired' or 'Daniel grabbed the apple' or both.
It is improbable that 'Jason is tired' or 'Daniel grabbed the apple' 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
  0.5::factA.
  0.1::factB.
  1.0::factC.
  %hop1
  0.9::factX:-xor(factC,factB).
  0.02::factY:-xor(factC,factB).
  0.2::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Jason is tired' or 'Daniel grabbed the apple' or both.