Help

[Nam-Ky Nguyen]

Dear colleagues,

Below are two resolvable IBDs with k=v/2: D1 and D2. D1 has
(v,k,r,b)=(6,3,7,14) and D2 has (v,k,r,b)=(6,3,9,18). As you can see,
D2 is an RGD and D1 is not an RGD (RGD solution is only available for
non-resolvable design). My question is for a given (v,k=v/2,r,b=2r),
how can we prove that the resolvable RGD solution does not exist for
this parameter set? 

Regards,
Nam Nguyen
P.S. Basically, this is the rewording of the question I asked last
week.

D1=
2  4  5  
0  1  3  
0  3  5  
1  2  4  
1  2  3  
0  4  5  
2  3  4  
0  1  5  
3  4  5  
0  1  2  
0  2  5  
1  3  4  
1  2  5  
0  3  4  

NN'=
7	3	2	3	2	4	
	7	4	3	2	2	
		7	2	3	3	
			7	4	2	
				7	3	
					7	

D2=
0  1  2  
3  4  5  
2  4  5  
0  1  3  
1  2  5  
0  3  4  
2  3  5  
0  1  4  
2  3  4  
0  1  5  
1  3  4  
0  2  5  
0  4  5  
1  2  3  
1  3  5  
0  2  4  
1  4  5  
0  2  3  

NN'=
9	4	4	3	4	3	
	9	3	4	3	4	
		9	4	3	4	
			9	4	3	
				9	4	
					9	

Nam-Ky Nguyen, Ph.D.
Design Computing
email: nkn at designcomputing.net
URL:   http://designcomputing.net/nkn/