On a classification of planar functions in characteristic three

Fuente: arXiv
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Main Authors: Andreoli, Samuele, Budaghyan, Lilya, Coulter, Robert, Haukenes, Alise, Kaleyski, Nikolay, Piccione, Enrico
Format: Preprint
Published: 2024
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author Andreoli, Samuele
Budaghyan, Lilya
Coulter, Robert
Haukenes, Alise
Kaleyski, Nikolay
Piccione, Enrico
author_facet Andreoli, Samuele
Budaghyan, Lilya
Coulter, Robert
Haukenes, Alise
Kaleyski, Nikolay
Piccione, Enrico
contents Planar functions are functions over a finite field that have optimal combinatorial properties and they have applications in several branches of mathematics, including algebra, projective geometry and cryptography. There are two relevant equivalence relations for planar functions, that are isotopic equivalence and CCZ-equivalence. Classification of planar functions is performed via CCZ-equivalence which arises from cryptographic applications. In the case of quadratic planar functions, isotopic equivalence, coming from connections to commutative semifields, is more general than CCZ-equivalence and isotopic transformations can be considered as a construction method providing up to two CCZ-inequivalent mappings. In this paper, we first survey known infinite classes and sporadic cases of planar functions up to CCZ-equivalence, aiming to exclude equivalent cases and to identify those with the potential to provide additional functions via isotopic equivalence. In particular, for fields of order $3^n$ with $n\le 11$, we completely resolve if and when isotopic equivalence provides different CCZ-classes for all currently known planar functions. Further, we perform an extensive computational investigation on some of these fields and find seven new sporadic planar functions over $\mathbb{F}_{3^6}$ and two over $\mathbb{F}_{3^9}$. Finally, we give new simple quadrinomial representatives for the Dickson family of planar functions.
format Preprint
id arxiv_https___arxiv_org_abs_2407_03170
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle On a classification of planar functions in characteristic three
Andreoli, Samuele
Budaghyan, Lilya
Coulter, Robert
Haukenes, Alise
Kaleyski, Nikolay
Piccione, Enrico
Combinatorics
Algebraic Geometry
Planar functions are functions over a finite field that have optimal combinatorial properties and they have applications in several branches of mathematics, including algebra, projective geometry and cryptography. There are two relevant equivalence relations for planar functions, that are isotopic equivalence and CCZ-equivalence. Classification of planar functions is performed via CCZ-equivalence which arises from cryptographic applications. In the case of quadratic planar functions, isotopic equivalence, coming from connections to commutative semifields, is more general than CCZ-equivalence and isotopic transformations can be considered as a construction method providing up to two CCZ-inequivalent mappings. In this paper, we first survey known infinite classes and sporadic cases of planar functions up to CCZ-equivalence, aiming to exclude equivalent cases and to identify those with the potential to provide additional functions via isotopic equivalence. In particular, for fields of order $3^n$ with $n\le 11$, we completely resolve if and when isotopic equivalence provides different CCZ-classes for all currently known planar functions. Further, we perform an extensive computational investigation on some of these fields and find seven new sporadic planar functions over $\mathbb{F}_{3^6}$ and two over $\mathbb{F}_{3^9}$. Finally, we give new simple quadrinomial representatives for the Dickson family of planar functions.
title On a classification of planar functions in characteristic three
topic Combinatorics
Algebraic Geometry
url https://arxiv.org/abs/2407.03170