We believe that Mary left the football. It is probably not the case that John put down the apple. It is unlikely that Bernhard is green. We doubt that if either 'Mary left the football' or 'Bernhard is green' but not both then Julius is white. It is probably not the case that if either 'Bernhard is green' or 'John put down the apple' but not both then Gertrude is a mouse. Chances are slight that if 'Mary left the football' or 'John put down the apple' or both then Brian is green.
There is a better than even chance that 'Brian is green and Mary left the football'.
Chances are slight that 'Brian is green and Mary left the football'.
There is a better than even chance that 'Brian is green and Mary left the football'.

  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
  0.75::factA.
  0.25::factB.
  0.2::factC.
  %hop1
  0.2::factX:-xor(factA,factC).
  0.25::factY:-xor(factC,factB).
  0.1::factZ:-or(factA,factB).

  %hop2
  conclusion:-and(factZ,factA).

  query(conclusion).
  
'Brian is green and Mary left the football'.