[php] tableau de tableau

Bonjour,

j'essaie de créer un tableau de tableau en php, mais j'ai une erreur et je ne comprends pas !

Notice: Undefined variable: lemonde in /var/www/html/news/webservice/parametre.php on line 18

mon code php
$choix = array($lemonde,$liberation,$nlObs,$figaro); --> ligne 18

$lemonde = array("lemonde","alaune","international","europe","economie","sport","culture","planete",
"politiques","cinema");

$liberation = array("liberation","alaune","monde","politiques","societes",",education","economie","terre",
"cultures","livres");

$nlObs = array("nouvelobservateur","alaune","europe","international","politiques","societes","environnement",
"economie","sciences","sports");

$figaro = Array("figaro","actualites","international","economie","bourses","rugby","foot","tennis","golf",
"formule1");

Merci pour votre aide

titi