<defs>
  <!-- le cercle original: celui qui est cloné -->
  <circle id="unCercle" r="16" stroke="black" fill="none"/>	
</defs>


<!-- le clone du haut -->
<use xlink:href="#unCercle" x="64" y="32"/>

<!-- les 2 clones du milieu -->
<use xlink:href="#unCercle" x="48" y="60"/>
<use xlink:href="#unCercle" x="80" y="60"/>

<!-- les 3 clones du bas -->
<use xlink:href="#unCercle" x="32" y="88"/>
<use xlink:href="#unCercle" x="64" y="88"/>
<use xlink:href="#unCercle" x="96" y="88"/>