It is probable that Brian is a rhino. It is probably not the case that Sandra left the milk. It is impossible that Jeff went to the garden. We believe that if 'Jeff went to the garden and Sandra left the milk' then Lily is green. There is little chance that if 'Sandra left the milk' or 'Jeff went to the garden' or both then Bernhard is a lion. It is probable that if 'Brian is a rhino' or 'Sandra left the milk' or both then Fred is in the office.
There is a very good chance that 'Bernhard is a lion' or 'Jeff went to the garden' or both.
There is almost no chance that 'Bernhard is a lion' or 'Jeff went to the garden' or both.
There is a very good chance that 'Bernhard is a lion' or 'Jeff went to the garden' 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.
  0.25::factB.
  0.0::factC.
  %hop1
  0.75::factX:-and(factC,factB).
  0.1::factY:-or(factB,factC).
  0.7::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Bernhard is a lion' or 'Jeff went to the garden' or both.