There is a better than even chance that Fred dropped the milk. It is probable that John put down the apple. It is highly unlikely that Brian is green. It is likely that if either 'Brian is green' or 'John put down the apple' but not both then Julius is gray. It is impossible that if either 'Brian is green' or 'Fred dropped the milk' but not both then Bernhard is a swan. It is unlikely that if 'John put down the apple and Brian is green' then Emily is a sheep.
Chances are about even that 'Emily is a sheep' or 'Brian is green' or both.
It is highly unlikely that 'Emily is a sheep' or 'Brian is green' or both.
Chances are about even that 'Emily is a sheep' or 'Brian is green' 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
  0.6::factA.
  0.7::factB.
  0.05::factC.
  %hop1
  0.7::factX:-xor(factC,factB).
  0.0::factY:-xor(factC,factA).
  0.2::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Emily is a sheep' or 'Brian is green' or both.