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								Kazuki Kumegawa
							
              						
 
											- 
							
								Ysukasa Okazaki
							
              						
 
											- 
							
								Tatsuya Maruta
							
              						
 
									
			
																												
							
									
				
										Keywords:
				
				
																		Optimal linear codes, 													Griesmer bound, 													Projective dual, 													Geometric puncturing															
			
			
										
					
Abstract
					We construct a lot of new $[n,4,d]_9$ codes whose lengths are close to the Griesmer bound and prove the nonexistence of some linear codes attaining the Griesmer bound using some geometric techniques through projective geometries to determine the exact value of $n_9(4,d)$ or to improve the known bound on $n_9(4,d)$ for given values of $d$, where $n_q(k,d)$ is the minimum length $n$ for which an $[n,k,d]_q$ code exists. We also give the updated table for $n_9(4,d)$ for all $d$ except some known cases.