How to check if different objects are already linked?

Hey guys,

I have following problem:

I created a kind of voronoi mesh and I now know the position of all vertices and which vertices belong to which polygon.

I know want to treat the vertices and the polygons as classes with handels and link them, so that each vertice knows which are its adjacend vertices and its adjacend polygons and each polygon knows which are the adjacend polygons and the vertices that define their borders.

My classes look like following:

classdef Vertex < handle
    properties
        position;
        neighbour_vertex;
        adjacend_polygon;
        
    end
   
    methods       
         
        function v = Vertex(pos)
            v.position = pos;
            v.neighbour_vertex = Vertex.empty(0,0);
            v.adjacend_polygon = Polygon.empty(0,0);
        end      
        
        % link vertex to vertex
        function link_v2v(v,neighbour)
            v.neighbour_vertex(end+1)=neighbour;
            neighbour.neighbour_vertex(end+1)=v;
        end


    end
end

classdef Polygon < handle
    properties
        rho
        adjacend_vertex;
        adjacend_polygon;

    end
   
    methods       
         
        function p = Polygon(rho)
            p.rho=rho;
            p.adjacend_vertex = Vertex.empty(0,0);
            p.adjacend_polygon = Polygon.empty(0,0); 

        end      
        
        % link polygon to vertex
        function link_v2p(p,vertex)
            for i=1:length(vertex)
                p.adjacend_vertex(end+1)=vertex(i);
                vertex(i).adjacend_polygon(end+1)=p;
            end
        end
       % link polygon to edge


       % link polygon to polygon
       function link_p2p(p)
           for i=1:length(p.adjacend_vertex)
               for j=1:length(p.adjacend_vertex(i).adjacend_polygon)
                   
                   if p.adjacend_vertex(i).adjacend_polygon(j)==p || p.adjacend_vertex(i).adjacend_polygon(j)==p.adjacend_polygon(end)
                       continue
                   else
                       p.adjacend_polygon(end+1)=p.adjacend_vertex(i).adjacend_polygon(j);
                   end
                   
               end
           end
       end
       
    end
end

I linked all object stogether as follows:

pos = vertices;
vertex = Vertex.empty(size(pos,1),0);
polygon=Polygon.empty(size(polygons,1),0);

for i = 1: size(pos,1)
    
    vertex(i) = Vertex(pos(i,:));
    
end

for i=1:length(edge)
    v1=edge(i,1);
    v2=edge(i,2);
    link_v2v(vertex(v1),vertex(v2));
end

rhos=10^12*random('unif',0.9,1.1,length(polygons),1);

for i=1:size(polygons,1)
    polygon(i)=Polygon(rhos(i));

end

for i=1:size(polygons,1)
    link_v2p(polygon(i),vertex(polygons{i}));
end

for i=1:length(polygon)
link_p2p(polygon(i));
end

But it doesnt work as planned. Since I find the polygons that are neighbours of a specific polygon, by looking for the already correctly linked vertices of that specific polygon and by looking for the adjacend polygons of those vertices, I double link them.... and since the polygon itsself is a adjacend polygon of its own vertices I link the polygon to itsself which I also do not want.

I got rid of the last point by the first expression in the if statement in the link p2p function in the polygon class, but the second statement that should prevent the double linking does not work...

How can i check if an object that i want to link to another object is already linked to that object?

Best regards

Marc