garbage collection / reference counting and php4

Hi! Does anybody know how php4 handles detached cliques from the root reference graph? I mean following with detached cliques: class A { var $ptr; } a=new A; //object 1 b=new A; //object 2 $a->ptr=$b; $b->ptr=$a; $a=0; $b=0; the reference count of these objects 1 and 2 is still 1 so they aren't free by reference counting, right? Are these cliques freed at the end of the script or is their a garbage collector that tried to find these cliques? Jan-Eric Duden