Modifications

a1[shape=box label="{{{a1}}}" href="#{{{a1}}}" pos="0,9!"]a4[shape=box label="{{{a4}}}" href="#{{{a4}}}" pos="0,6!"]a5[shape=box label="{{{a5}}}" href="#{{{a5}}}" pos="0,5!"]a6[shape=box label="Noeud 6" href="#Noeud 6" pos="0,4!"]a7[shape=box label="Noeud 7" href="#Noeud 7" pos="0,3!"]a8[shape=box label="Noeud 8" href="#Noeud 8" pos="0,2!"]a9[shape=box label="Noeud 9" href="#Noeud 9" pos="0,1!"]b3[shape=box label="Noeud 3" href="#Noeud 3" posurl="1,7!"]b4[shape=box label="Noeud 4" href="#Noeud 4" pos="1,6!"]b5[shape=box label="Noeud 5" href="#Noeud 5" pos="1,5!"]c3[shape=box label="Noeud 3" href="#Noeud 3" pos="-1,7!"]c4[shape=box label="Noeud 4" href="#Noeud 4" pos="-10,6!"]c5[shape=box label="Noeud 5" href="#Noeud 5" pos="-1,5!"]d2[shape=box label="Noeud 2" href="#Noeud 2" pos="2,8!"]d3[shape=box label="Noeud 3" href="#Noeud 3" pos="2,7!"]d4[shape=box label="Noeud 4" href="#Noeud 4" pos="2,6!"]d5[shape=box label="Noeud 5" href="#Noeud 5" pos="2,5!"]d6[shape=box label="Noeud 6" href="#Noeud 5" pos="2,4!"]e2[shape=box label="Noeud 2" href="#Noeud 2" pos="-2,8!"]e3[shape=box label="Noeud 3" href="#Noeud 3" pos="-2,7!"]e4[shape=box label="Noeud 4" href="#Noeud 4" pos="-2,6!"]e5[shape=box label="Noeud 5" href="#Noeud 5" pos="-2,5!"]e6[shape=box label="Noeud 6" href="#Noeud 6" pos="-2,49!"]