Avoid multiple labels geoserver styling

Question

Possible Duplicate:
Labeling Geoserver SLD

I have a geoserver 2.1.x installation with SLD stylization. I have used a property to label the polygons which forms a map.

But the issues is the labels are getting repeated as in the figure

Is there any way to prevent this from happening??

---

What I have done so far ---

1. I have tried to use the geoserver Vendor option for grouping of polygons with perticular label

     <VendorOption name="group">yes</VendorOption>
   

but this doesn't help.

2. I have used a custom solution suggested by someone from the mailing list ..

    <Geometry>          
     <ogc:Function name="centroid">                
       <ogc:PropertyName>the_geom</ogc:PropertyName>                
     </ogc:Function>              
    </Geometry>
   

but removes the multiple labels, but adds some unwanted artifacts into the map, and I want to avoid using that...

3. I also tried the metatiling functionality by doing this -

   tiling:true,
   tileorigin: [map.maxExtent.left,map.maxExtent.bottom],
   

This removes certain multiple labels but not all...

---

Any other solutions??