private Collection<char[]> getDomainValues(int cols, int row,int start_pos) {
        List<char[]> vals=new LinkedList();

        char[] basic=new char[cols];
        int pos=start_pos;
        for(int j=0;j<pos;j++){
            basic[j]='_';
        }

        for(Pair p:unary.rows[row].pairs){
            for(int j=pos;j<pos+p.count;j++){
                if(j>=cols){
                    return vals;
                }
                basic[j]=p.color;
            }
            pos+=p.count;
        }
        for(int j=pos;j<cols;j++){
            basic[j]='_';
        }

        vals.add(basic);
        vals.addAll(getDomainValues(cols,row,start_pos+1));

        vals.addAll(getVariants(basic,row,start_pos));

        return vals;
    }

    private Collection<char[]> getVariants(char[] basic,int row,int start_pos) {
        List<char[]> vals=new LinkedList();

        for(Pair p:unary.rows[row].pairs){
            boolean add=true;
            char prev=basic[start_pos+unary.rows[row].pairs.get(0).count-1];
            for(int j=start_pos+unary.rows[row].pairs.get(0).count;j<cols;j++){
                char pom=basic[j];
                if(pom!='_' && j+1>=cols){
                    add=false;
                    break;
                }
                basic[j]=prev;
                prev=pom;
            }
            if(add){
                vals.add(basic);
                vals.addAll(getVariants(basic,row,start_pos));
            }
        }

        return vals;
    }