We doubt that Bernhard is green. Chances are slight that Winona is a sheep. It is probable that Sandra left the milk. There is almost no chance that if 'Bernhard is green' or 'Winona is a sheep' or both then Lily is a rhino. It is impossible that if 'Bernhard is green and Sandra left the milk' then John went to the kitchen. There is a better than even chance that if 'Bernhard is green' or 'Winona is a sheep' or both then Mary moved to the office.
There is a very good chance that 'Winona is a sheep and Sandra left the milk'.
It is highly unlikely that 'Winona is a sheep and Sandra left the milk'.
There is a very good chance that 'Winona is a sheep and Sandra left the milk'.

  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
  0.2::factA.
  0.1::factB.
  0.7::factC.
  %hop1
  0.02::factX:-or(factA,factB).
  0.0::factY:-and(factA,factC).
  0.6::factZ:-or(factA,factB).

  %hop2
  conclusion:-and(factB,factC).

  query(conclusion).
  
'Winona is a sheep and Sandra left the milk'.