It is certain that John went to the office. It is certain that Winona is a wolf. It is likely that Fred put down the apple. We believe that if either 'Winona is a wolf' or 'Fred put down the apple' but not both then Brian is a lion. It is highly unlikely that if either 'Fred put down the apple' or 'John went to the office' but not both then Julius is a swan. Chances are about even that if 'Winona is a wolf and John went to the office' then Jason is tired.
It is unlikely that 'Fred put down the apple' or 'Brian is a lion' or both.
It is almost certain that 'Fred put down the apple' or 'Brian is a lion' or both.
It is unlikely that 'Fred put down the apple' or 'Brian is a lion' 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
  1.0::factA.
  1.0::factB.
  0.7::factC.
  %hop1
  0.75::factX:-xor(factB,factC).
  0.05::factY:-xor(factC,factA).
  0.5::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Fred put down the apple' or 'Brian is a lion' or both.