We doubt that Sandra left the milk. Chances are slight that Brian is white. It is probably not the case that Greg is yellow. It is highly unlikely that if 'Brian is white' or 'Greg is yellow' or both then Lily is a lion. There is almost no chance that if 'Greg is yellow' or 'Brian is white' or both then Fred went to the garden. It is improbable that if 'Greg is yellow' or 'Sandra left the milk' or both then Mary moved to the office.
There is a very good chance that 'Sandra left the milk and Mary moved to the office'.
There is almost no chance that 'Sandra left the milk and Mary moved to the office'.
There is a very good chance that 'Sandra left the milk and Mary moved to the office'.

  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.
  0.25::factC.
  %hop1
  0.05::factX:-or(factB,factC).
  0.02::factY:-or(factC,factB).
  0.1::factZ:-or(factC,factA).

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

  query(conclusion).
  
'Sandra left the milk and Mary moved to the office'.