For a finite group $G$, let $\mathsf{d}(G)$ denote the maximum length of a sequence having no nonempty subsequence whose terms can be ordered to have product one. For an odd prime $p$, let $H_{p^3}=\operatorname{UT}*3(\mathbb{F}*p)$. Godara and Sarkar proved $\mathsf{d}(H*{27})=6$ and conjectured $\mathsf{d}(H*{p^3})=3p-3$; in a recent preprint, White proved the next case $\mathsf{d}(H_{125})=12$ and left $18\leq\mathsf{d}(H_{343})\leq24$. We prove $\mathsf{d}(H_{343})=18$. We adopt White's product-one criterion and spread framework and develop a $p=7$-specific direction stratification. An explicit product-one-free sequence gives the lower bound. For the upper bound, we stratify a hypothetical product-one-free sequence of length $19$ by the number of central terms and by the occupied projective directions of its quotient multiset. Supports on at most two directions are excluded by a theoretical argument whose finite auxiliary statements are exhaustively checked; the three-direction case and the case of five central terms are settled by exact finite computations. The remaining thirty strata are encoded by a counterexample-guided SAT procedure. A separately implemented checker verifies all $9{,}920{,}815$ seed cuts and all $27{,}207$ learned cuts, and each final unsatisfiable instance is accompanied by a checked LRAT certificate. A separate implementation-level audit verifies the master encoding, the proof archives, and the lower-bound witness.
The small Davenport constant $\mathsf{d}(G)$ of a finite group $G$ is the maximal length of a product-one-free sequence over $G$. For the exponent-$p$ Heisenberg group $H_{p^3}$ of order $p^3$, Godara and Sarkar proved $\mathsf{d}(H_{27})=6$ and posed $\mathsf{d}(H_{p^3})=3p-3$ for every odd prime $p$, leaving $p\ge5$ open. We settle the first open case: $\mathsf{d}(H_{125})=12$. The lower bound is the explicit product-one-free sequence $x^4y^4v^4$. For the upper bound we record a product-one criterion that reduces the non-commutative problem to additive combinatorics over $\mathbb{F}_5^2$, and then reduce"every length-13 sequence has a product-one subsequence"to a single finite statement -- a spread bound on quotient multisets -- which we verify by an exhaustive, memory-flat search in C, its verdict independently reproduced by a second search with a different pruning strategy. Every auxiliary lemma is machine-checked. The argument is genuinely $p$-specific: we identify the exact step that fails for $p\ge7$ (a Chevalley-Warning shortcut whose forced block need not be wide), exhibit the obstructing multiset for $p=7$, and leave only $18\le\mathsf{d}(H_{343})\le24$. The techniques -- the Cauchy-Davenport theorem, Chevalley-Warning, and Olson's value of the Davenport constant of $C_p^2$ -- are standard; the contribution is their assembly against a new non-abelian target and the finite verification that closes it.
Let $p$ be an odd prime and let $H_{p^3}=\operatorname{UT}_3(\mathbb{F}_p)$ be the Heisenberg group of order $p^3$ and exponent $p$. We prove $\mathsf{d}(H_{p^3})=3p-3$. The main ingredient of the proof is an order-value growth theorem. If $B$ is a noncollinear zero-sum sequence of $n$ nonzero vectors in $\mathbb{F}_p^2$, then the alternating areas obtained by ordering $B$ assume at least $\min(p,n-1)$ distinct values. Its proof is a short contraction induction: contract a suitable independent pair, replace the contracted vector in both orders, and apply Cauchy--Davenport. A polynomial relative-subsum theorem and a sharp representation-rigidity lemma then turn this local growth into a uniform spread bound. Combined with the standard product-one criterion for $H_{p^3}$, the spread bound yields the upper bound; the usual sequence $x^{p-1}y^{p-1}v^{p-1}$ gives the lower bound.
The Hurwitz bound on the order of the $\mathbb K$-automorphism group ${\rm{Aut}}({\mathcal{X}})$ of an algebraic curve ${\mathcal{X}}$ of genus $g(\mathcal{X})\ge 2$ defined over a field $\mathbb K$ of zero characteristic states that $|{\rm{Aut}}({\mathcal{X}})|\le 84(g(\mathcal{X})-1)$. Improved bounds are available for the order of certain types of subgroups within automorphism groups. For instance, if a subgroup $H$ of ${\rm{Aut}}({\mathcal{X}})$ is dihedral, then in the complex case, $|H| \leq 4g(\mathcal{X}) + 4$. More recently it has been shown that a tighter bound holds for $H$ a generalized quasi-dihedral group. In this paper we explore the more general setting of a curve defined over a field of any characteristic, and $H$ a group admitting a cyclic subgroup of index two. We show that the same upper bound for the size of a dihedral group of automorphisms holds for curves defined over an algebraically closed field of characteristic $p\ne 2$. Then we provide some classification results about (non-dihedral) groups of size larger than $4g(\mathcal{X})+4$ admitting a cyclic subgroup of index $2$.
Arianna Dionigi, Massimo Giulietti, Marco Timpanella· 0 citations
Let $G$ be a finite nonabelian group. The small Davenport constant $\mathsf d(G)$ of $G$ is the largest integer $\ell$ such that there exists a product-one free sequence over $G$ of length $\ell$, while the Gao constant $E(G)$ of $G$ is the least integer $\ell$ such that every sequence over $G$ of length at least $\ell$ contains a product-one subsequence of length exactly $|G|$. A long-standing conjecture of Gao and Zhuang \cite{ZG2005} asserts that $E(G)=\mathsf d(G)+|G|$ for every finite nonabelian group $G$. Let $p$ be an odd prime and let $H_{p^3}=\operatorname{UT}_3(\mathbb F_p)$ be the finite Heisenberg group over $\mathbb F_p$. Godara and Sarkar proved the Gao-Zhuang equality for $H_{27}=\operatorname{UT}_3(\mathbb F_3)$ and asked whether the same equality holds for $H_{p^3}$ for every odd prime $p$. Recently, Volkmann proved that $\mathsf d(H_{p^3})=3p-3$. In this paper, we determine the Gao constant of $H_{p^3}$ and prove that $E(H_{p^3})=\mathsf d(H_{p^3})+|H_{p^3}|=p^3+3p-3$. Together with the known abelian and cyclic-index cases, this completes the verification of the Gao-Zhuang equality for all groups of order $p^3$, for every prime $p$.
UDC 512.552
Suppose that $\mathcal{H}_1, \mathcal{H}_2$ and $\mathcal{H}_3$ are generalized skew derivations on prime ring $\mathcal{R}$ with ${\rm char}(\mathcal{R})\neq 2$ such that $\mathcal{H}_1\big(\mathcal{H}_2(\pi(q))\pi(q)\big)=\mathcal{H}_3(\pi(q)^2)$ for all $q=(q_1,\ldots,q_n) \in \mathcal{R}^n,$ where $\pi(q_1,\ldots,q_n)$ denotes the multilinear polynomial over $\mathcal{C},$ which is noncentral and nonidentity. We present all possible configurations of the maps $\mathcal{H}_1, \mathcal{H}_2,$ and $\mathcal{H}_3.$ This extends the results obtained by V. de Filippis [Comm. Algebra, 49, No. 7, 2987–3009 (2021)].
Pallavee Gupta, S. K. Tiwari, Lovepreet Singh· Ukrains'kyi Matematychnyi Zh...· 0 citations
Let $F$ and $E$ be finite extensions of $\mathbb Q_p$, let $\mathbb G$ be a reductive group over $F$, and put $G=\mathbb G(F)$. Let $V$ be a locally algebraic representation of the form $V=\pi_{\mathrm{sm}}\otimes_E\sigma_{\mathrm{alg}}$, where $\pi_{\mathrm{sm}}$ is smooth admissible and $\sigma_{\mathrm{alg}}$ is finite-dimensional algebraic. We study the extended Goldman--Iwahori distance on the set of non-Archimedean norms on $V$. After fixing a reference norm $\alpha_0$, its finite-distance component $\mathscr N_{\alpha_0}(V)$ is the bounded projective limit of the extended Bruhat--Tits buildings attached to $V_K=\pi_{\mathrm{sm}}^K\otimes_E\sigma_{\mathrm{alg}}$. It is complete for the resulting uniform sup metric; this metric is of $\ell^\infty$ type and is generally not CAT(0). We prove directly that a $G$-orbit in $\mathscr N_{\alpha_0}(V)$ is bounded if and only if this component contains a $G$-invariant norm. The invariant norm is the pointwise supremum of the orbit. We formulate an integral group-algebra and type-Hecke condition necessary for an invariant norm. For $G=GL_n(F)$ we specialise to $V=\operatorname{BS}(r)=\pi_{\mathrm{gen}}(r)\otimes_E \pi_{\mathrm{alg}}(r)$.
A. Pyvovarov· 0 citations
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