It is probably the case that Jeff left the apple. It is highly likely that Mary moved to the office. It is likely that John put down the apple. Chances are slight that if either 'John put down the apple' or 'Jeff left the apple' but not both then Bill got the milk there. It is probable that if 'John put down the apple' or 'Jeff left the apple' or both then Brian is white. It is probably not the case that if 'Mary moved to the office and John put down the apple' then Julius is a lion.
It is unlikely that 'Julius is a lion' or 'Bill got the milk there' or both.
It is unlikely that 'Julius is a lion' or 'Bill got the milk there' or both.
It is almost certain that 'Julius is a lion' or 'Bill got the milk there' 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.
  0.9::factB.
  0.7::factC.
  %hop1
  0.1::factX:-xor(factC,factA).
  0.7::factY:-or(factC,factA).
  0.25::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Julius is a lion' or 'Bill got the milk there' or both.