On quadratic residue codes and hyperelliptic curves

Sumsets in quadratic residues

We describe all sets $A \subseteq \F_p$ which represent the quadratic residues $R \subseteq \F_p$ as $R=A+A$ and $R=A\hat{+} A$. Also, we consider the case of an approximate equality $R \approx A+A$ and $R \approx A\hat{+} A$ and prove that $A$ has a structure in the situation.

A note on Linnik's Theorem on quadratic non-residues

We present a short, self-contained, and purely combinatorial proof of Linnik's theorem: for any $\varepsilon > 0$ there exists a constant $C_\varepsilon$ such that for any $N$, there are at most $C_\varepsilon$ primes $p \leqslant N$ such that the least positive quadratic non-residue modulo $p$ exceeds $N^\varepsilon$.

Counting Additive Decompositions of Quadratic Residues in Finite Fields

We say that a set $S$ is additively decomposed into two sets $A$ and $B$ if $S = \{a+b : a\in A, \ b \in B\}$. A. Sárközy has recently conjectured that the set $Q$ of quadratic residues modulo a prime $p$ does not have nontrivial decompositions. Although various partial results towards this conjecture have been obtained, it is still open. Here we obtain a nontrivial upper bound on the number of such decompositions.

论二次剩余的分布

On the distribution of quadratic residues

该研究运用加性组合方法探究素数域平方数集合的分布，得出当前该集合间隔数的最佳上界，且将结果拓展至小倍增集合，推进了二次剩余分布相关研究。

二次剩余与多米诺骨牌平铺

Quadratic residues and domino tilings

该研究发现多米诺骨牌平铺数公式与Legendre符号公式的相似性，探究二者关联并证明了用多米诺骨牌平铺表示Jacobi符号的公式，搭建起数论与组合数学间的新联系。

Quadratic residues and related permutations and identities

Let $p$ be an odd prime. In this paper we investigate quadratic residues modulo $p$ and related permutations, congruences and identities. If $a_1<\ldots<a_{(p-1)/2}$ are all the quadratic residues modulo $p$ among $1,\ldots,p-1$, then the list $\{1^2\}_p,\ldots,\{((p-1)/2)^2\}_p$ (with $\{k\}_p$ the least nonnegative residue of $k$ modulo $p$) is a permutation of $a_1,\ldots,a_{(p-1)/2}$, and we show that the sign of this permutation is $1$ or $(-1)^{(h(-p)+1)/2}$ according as $p\equiv3\pmod 8$ or $p\equiv7\pmod 8$, where $h(-p)$ is the class number of the imaginary quadratic field $\mathbb Q(…

New Extremal Binary Self-Dual Codes from Block Circulant Matrices and Block Quadratic Residue Circulant Matrices

In this paper, we construct self-dual codes from a construction that involves both block circulant matrices and block quadratic residue circulant matrices. We provide conditions when this construction can yield self-dual codes. We construct self-dual codes of various lengths over F2 and F2 + uF2. Using extensions, neighbours and sequences of neighbours, we construct many new self-dual codes. In particular, we construct one new self-dual code of length 66 and 51 new self-dual codes of length 68.

有限域中二次剩余的VC维数

The VC-dimension of quadratic residues in finite fields

本文研究有限域中二次剩余集合的VC维数，猜想其渐近达到最大可能值，并利用Weil界证明了下界，同时将结果推广到有界指数乘法子群。

Quantum Algorithms for Weighing Matrices and Quadratic Residues

In this article we investigate how we can employ the structure of combinatorial objects like Hadamard matrices and weighing matrices to device new quantum algorithms. We show how the properties of a weighing matrix can be used to construct a problem for which the quantum query complexity is ignificantly lower than the classical one. It is pointed out that this scheme captures both Bernstein & Vazirani's inner-product protocol, as well as Grover's search algorithm. In the second part of the article we consider Paley's construction of Hadamard matrices, which relies on the properties of quadrati…

Trigonometric identities and quadratic residues

In this paper we obtain some novel identities involving trigonometric functions. Let $n$ be any positive odd integer. We show that $$\sum_{r=0}^{n-1}\frac1{1+\sin2π\frac{x+r}n+\cos2π\frac{x+r}n} =\frac{(-1)^{(n-1)/2}n}{1+(-1)^{(n-1)/2}\sin 2πx+\cos 2πx}$$ for any complex number with $x+1/2,x+(-1)^{(n-1)/2}/4\not\in\mathbb Z$, and $$\sum_{j,k=0}^{n-1}\frac1{\sin 2π\frac{x+j}n+\sin2π\frac{y+k}n}=\frac{(-1)^{(n-1)/2}n^2}{\sin 2πx+\sin2πy}$$ for all complex numbers $x$ and $y$ with $x+y,x-y-1/2\not\in\mathbb Z$. We also determine the values of $\prod_{k=1}^{(p-1)/2}(1+\tanπ\frac{k^2}p)$ and $\prod…