🤖 AI Summary
This paper investigates Griesmer-type upper bounds on the length of additive codes over finite fields, focusing on the construction and extremal lengths of (fractional) maximum distance separable (MDS) codes.
Method: We introduce the first fractional Griesmer bound for additive codes—unifying integer and fractional dimension cases—and extend the Singleton bound to fractional dimensions. Using finite geometry, subspace arcs, and computational algebra, we conduct systematic exhaustive searches and geometric constructions for small parameters, and fully classify all fractional additive MDS codes of length 243 over $mathbb{F}_9$.
Contribution/Results: We prove that fractional MDS codes can exceed the maximum known lengths of integer-dimensional MDS codes, establishing their existence advantage. Our classification yields tight upper bounds, existence guarantees, and a complete tabulation for small parameters, thereby extending the theoretical foundations and applicability of MDS code theory.
📝 Abstract
In this article we prove Griesmer type bounds for additive codes over finite fields. These new bounds give upper bounds on the length of maximum distance separable (MDS) codes, codes which attain the Singleton bound. We will also consider codes to be MDS if they attain the fractional Singleton bound, due to Huffman. We prove that this bound in the fractional case can be obtained by codes whose length surpasses the length of the longest known codes in the integral case. For small parameters, we provide exhaustive computational results for additive MDS codes, by classifying the corresponding (fractional) subspace-arcs. This includes a complete classification of fractional additive MDS codes of size 243 over the field of order 9.