<p>We consider a subclass of <i>p</i>-ary self-reversible generalized (<i>L</i>,&#xa0;<i>G</i>) codes with a locator set <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10623_2025_1648_Article_IEq1.gif" Format="GIF" Height="24" Rendition="HTML" Resolution="72" Type="Linedraw" Width="322" /> </InlineMediaObject> <EquationSource Format="TEX">\(L=\{ \frac{2x-\alpha }{x^2-\alpha x +1},\alpha \in \mathbb {F}_q \setminus \{0\}, q=p^m \} \cup \{\frac{1}{x+1}\}\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>L</mi> <mo>=</mo> <mrow> <mo stretchy="false">{</mo> <mfrac> <mrow> <mn>2</mn> <mi>x</mi> <mo>-</mo> <mi>α</mi> </mrow> <mrow> <msup> <mi>x</mi> <mn>2</mn> </msup> <mo>-</mo> <mi>α</mi> <mi>x</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> <mo>,</mo> <mi>α</mi> <mo>∈</mo> <msub> <mi mathvariant="double-struck">F</mi> <mi>q</mi> </msub> <mo lspace="0.15em" rspace="0.15em" stretchy="false">\</mo> <mrow> <mo stretchy="false">{</mo> <mn>0</mn> <mo stretchy="false">}</mo> </mrow> <mo>,</mo> <mi>q</mi> <mo>=</mo> <msup> <mi>p</mi> <mi>m</mi> </msup> <mo stretchy="false">}</mo> </mrow> <mo>∪</mo> <mrow> <mo stretchy="false">{</mo> <mfrac> <mn>1</mn> <mrow> <mi>x</mi> <mo>+</mo> <mn>1</mn> </mrow> </mfrac> <mo stretchy="false">}</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, where <i>p</i> is a prime number. The numerator <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10623_2025_1648_Article_IEq2.gif" Format="GIF" Height="14" Rendition="HTML" Resolution="72" Type="Linedraw" Width="53" /> </InlineMediaObject> <EquationSource Format="TEX">\(2x-\alpha \)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mn>2</mn> <mi>x</mi> <mo>-</mo> <mi>α</mi> </mrow> </math></EquationSource> </InlineEquation> of a rational function is the formal derivative of the denominator <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10623_2025_1648_Article_IEq3.gif" Format="GIF" Height="17" Rendition="HTML" Resolution="72" Type="Linedraw" Width="87" /> </InlineMediaObject> <EquationSource Format="TEX">\(x^2-\alpha x +1\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msup> <mi>x</mi> <mn>2</mn> </msup> <mo>-</mo> <mi>α</mi> <mi>x</mi> <mo>+</mo> <mn>1</mn> </mrow> </math></EquationSource> </InlineEquation>. The Goppa polynomial <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10623_2025_1648_Article_IEq4.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="92" /> </InlineMediaObject> <EquationSource Format="TEX">\(G(x) \in \mathbb {F}_q[x]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>G</mi> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mo>∈</mo> <msub> <mi mathvariant="double-struck">F</mi> <mi>q</mi> </msub> <mrow> <mo stretchy="false">[</mo> <mi>x</mi> <mo stretchy="false">]</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> of degree 2<i>t</i>, <i>t</i> being odd, is either an irreducible self-reversible polynomial of degree 2<i>t</i>, or a non-irreducible self-reversible polynomial of degree 2<i>t</i> of the form <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10623_2025_1648_Article_IEq5.gif" Format="GIF" Height="21" Rendition="HTML" Resolution="72" Type="Linedraw" Width="201" /> </InlineMediaObject> <EquationSource Format="TEX">\(G_1^{-1}(0)\cdot G_1(x)\cdot x^t\cdot G_1(x^{-1})\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mi>G</mi> <mn>1</mn> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msubsup> <mrow> <mo stretchy="false">(</mo> <mn>0</mn> <mo stretchy="false">)</mo> </mrow> <mo>·</mo> <msub> <mi>G</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mo>·</mo> <msup> <mi>x</mi> <mi>t</mi> </msup> <mo>·</mo> <msub> <mi>G</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <msup> <mi>x</mi> <mrow> <mo>-</mo> <mn>1</mn> </mrow> </msup> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation>, where <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="10623_2025_1648_Article_IEq6.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="98" /> </InlineMediaObject> <EquationSource Format="TEX">\(G_1(x)\in \mathbb {F}_q[x]\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msub> <mi>G</mi> <mn>1</mn> </msub> <mrow> <mo stretchy="false">(</mo> <mi>x</mi> <mo stretchy="false">)</mo> </mrow> <mo>∈</mo> <msub> <mi mathvariant="double-struck">F</mi> <mi>q</mi> </msub> <mrow> <mo stretchy="false">[</mo> <mi>x</mi> <mo stretchy="false">]</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> is any irreducible non self-reversible polynomial of degree <i>t</i>. Estimates for minimum distance and redundancy are obtained for codes from this subclass. It is shown that among these codes, there are codes lying on the Gilbert–Varshamov bound. As a special case, binary codes from this subclass that contains codes lying also on Gilbert–Varshamov bound are considered.</p>

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Self-reversible generalized (L,G)-codes

  • Sergey Bezzateev,
  • Natalia Shekhunova

摘要

We consider a subclass of p-ary self-reversible generalized (LG) codes with a locator set \(L=\{ \frac{2x-\alpha }{x^2-\alpha x +1},\alpha \in \mathbb {F}_q \setminus \{0\}, q=p^m \} \cup \{\frac{1}{x+1}\}\) L = { 2 x - α x 2 - α x + 1 , α F q \ { 0 } , q = p m } { 1 x + 1 } , where p is a prime number. The numerator \(2x-\alpha \) 2 x - α of a rational function is the formal derivative of the denominator \(x^2-\alpha x +1\) x 2 - α x + 1 . The Goppa polynomial \(G(x) \in \mathbb {F}_q[x]\) G ( x ) F q [ x ] of degree 2t, t being odd, is either an irreducible self-reversible polynomial of degree 2t, or a non-irreducible self-reversible polynomial of degree 2t of the form \(G_1^{-1}(0)\cdot G_1(x)\cdot x^t\cdot G_1(x^{-1})\) G 1 - 1 ( 0 ) · G 1 ( x ) · x t · G 1 ( x - 1 ) , where \(G_1(x)\in \mathbb {F}_q[x]\) G 1 ( x ) F q [ x ] is any irreducible non self-reversible polynomial of degree t. Estimates for minimum distance and redundancy are obtained for codes from this subclass. It is shown that among these codes, there are codes lying on the Gilbert–Varshamov bound. As a special case, binary codes from this subclass that contains codes lying also on Gilbert–Varshamov bound are considered.