It is improbable that Fred went to the garden. It is probably the case that Gertrude is a cat. It is likely that Brian is a rhino. It is probably the case that if 'Brian is a rhino' or 'Gertrude is a cat' or both then Emily is a wolf. It is likely that if either 'Fred went to the garden' or 'Brian is a rhino' but not both then Mary dropped the milk. It is impossible that if 'Brian is a rhino and Fred went to the garden' then John moved to the office.
Chances are about even that 'Fred went to the garden' or 'Mary dropped the milk' or both.
Chances are about even that 'Fred went to the garden' or 'Mary dropped the milk' or both.
It is impossible that 'Fred went to the garden' or 'Mary dropped the milk' 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
  0.1::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  0.7::factX:-or(factC,factB).
  0.7::factY:-xor(factA,factC).
  0.0::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Fred went to the garden' or 'Mary dropped the milk' or both.