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Jianya Liu

Publications and source records attributed to Jianya Liu.

At least 19 recordsLinked to original sources

Theorem $(1+1.9)$ on the Goldbach Conjecture

For $1 \leq a \leq 2$, we say Proposition $(1+a)$ holds if every sufficiently large even integer $N$ can be written as $$N = p + rq, \quad r \leq q^{a-1},$$ where $r$ is either $1$ or prime, and $p,q$ are primes. Thus Proposition $(1+1)$ is essentially the binary Goldbach Conjecture, and Proposition $(1+2)$ is Chen's theorem. We prove unconditionally that Proposition $(1+1.9)$ is true. Assuming the Elliott--Halberstam Conjecture, the exponent $1.9$ can be improved to $1.4$. Analogously, Proposition $(1-a)$ is formulated for the Twin Prime Conjecture. Unconditionally, we prove Proposition $(1-1.75)$, and under the Elliott--Halberstam Conjecture, Proposition $(1-1.4)$. For six decades, a substantial theoretical divide has persisted between Propositions $(1+2)$ and $(1+1)$, and likewise between Propositions $(1-2)$ and $(1-1)$. By constructing new weighted sieves and adopting new analytic tools, this paper establishes a connecting pathway between them and achieves breakthroughs in this line of research.

math.NT

Multiple Gauss sums

A multiple Gauss sum is a complete multiple exponential sum twisted by Dirichlet characters. We prove a new bound for multiple Gauss sums and, as an application, improve previous results in the Birch--Goldbach problem. Let $F_1, \ldots, F_R \in \mathbb{Z}[x_1, \ldots, x_s]$ be forms with differing degrees, with $D$ being the highest degree, and let $\boldsymbol{F} = (F_1, \ldots, F_R)$ be nonsingular. We prove that the system $\boldsymbol{F}(\boldsymbol{x})=\mathbf{0}$ is solvable in primes provided that $s \geq D^2 4^{D+2} R^5$.

math.NT

Anisotropic quadratic equations in three variables

Let $f(x_1, x_2, x_3)$ be an indefinite anisotropic integral quadratic form with determinant $d(f)$, and $t$ a non-zero integer such that $d(f)t$ is square-free. It is proved in this paper that, as long as there is one integral solution to $f(x_1, x_2, x_3) = t$, there are infinitely many such solutions for which (i) $x_1$ has at most $6$ prime factors, and (ii) the product $x_1 x_2$ has at most $16$ prime factors. Various methods, such as algebraic theory of quadratic forms, harmonic analysis, Jacquet-Langlands theory, as well as combinatorics, interact here, and the above results come from applying the sharpest known bounds towards Selberg's eigenvalue conjecture. Assuming the latter the number $6$ or $16$ may be reduced to $5$ or $14$, respectively.

math.NT

Forms in prime variables and differing degrees

Let $F_1,\ldots,F_R$ be homogeneous polynomials with integer coefficients in $n$ variables with differing degrees. Write $\boldsymbol{F}=(F_1,\ldots,F_R)$ with $D$ being the maximal degree. Suppose that $\boldsymbol{F}$ is a nonsingular system and $n\ge D^2 4^{D+6}R^5$. We prove an asymptotic formula for the number of prime solutions to $\boldsymbol{F}(\boldsymbol{x})=\boldsymbol{0}$, whose main term is positive if (i) $\boldsymbol{F}(\boldsymbol{x})=\boldsymbol{0}$ has a nonsingular solution over the $p$-adic units $\mathbb{U}_p$ for all primes $p$, and (ii) $\boldsymbol{F}(\boldsymbol{x})=\boldsymbol{0}$ has a nonsingular solution in the open cube $(0,1)^n$. This can be viewed as a smooth local-global principle for $\boldsymbol{F}(\boldsymbol{x})=\boldsymbol{0}$ with differing degrees. It follows that, under (i) and (ii), the set of prime solutions to $\boldsymbol{F}(\boldsymbol{x})=\boldsymbol{0}$ is Zariski dense in the set of its solutions.

math.NT

Manin's conjecture for singular cubic hypersurfaces

Let S Q denote x 3 = Q(y 1 ,. .. , y m)z where Q is a primitive positive definite quadratic form in m variables with integer coefficients. This S Q ranges over a class of singular cubic hypersurfaces as Q varies. For S Q we prove (i) Manin's conjecture is true if Q is locally determined with 2 | m and m 4; (ii) in general Manin's conjecture is true up to a leading constant if 2 | m and m 6.

math.NT

Representation by sums of unlike powers

It is proved that all sufficiently large integers $n$ can be represented as $$n=x_1^2+x_2^3+\cdots+x_{13}^{14},$$ where $x_1,\ldots,x_{13}$ are positive integers. This improves upon the current record with $14$ variables in place of $13$.

math.NT

On forms in prime variables

Let $F_1,\ldots,F_R$ be homogeneous polynomials of degree $d\ge 2$ with integer coefficients in $n$ variables, and let $\mathbf{F}=(F_1,\ldots,F_R)$. Suppose that $F_1,\ldots,F_R$ is a non-singular system and $n\ge 4^{d+2}d^2R^5$. We prove that there are infinitely many solutions to $\mathbf{F}(\mathbf{x})=\mathbf{0}$ in prime coordinates if (i) $\mathbf{F}(\mathbf{x})=\mathbf{0}$ has a non-singular solution over the $p$-adic units $\U_p$ for all prime numbers $p$, and (ii) $\mathbf{F}(\mathbf{x})=\mathbf{0}$ has a non-singular solution in the open cube $(0,1)^n$.

math.NT

Subsampling Bias and The Best-Discrepancy Systematic Cross Validation

Statistical machine learning models should be evaluated and validated before putting to work. Conventional k-fold Monte Carlo Cross-Validation (MCCV) procedure uses a pseudo-random sequence to partition instances into k subsets, which usually causes subsampling bias, inflates generalization errors and jeopardizes the reliability and effectiveness of cross-validation. Based on ordered systematic sampling theory in statistics and low-discrepancy sequence theory in number theory, we propose a new k-fold cross-validation procedure by replacing a pseudo-random sequence with a best-discrepancy sequence, which ensures low subsampling bias and leads to more precise Expected-Prediction-Error estimates. Experiments with 156 benchmark datasets and three classifiers (logistic regression, decision tree and naive bayes) show that in general, our cross-validation procedure can extrude subsampling bias in the MCCV by lowering the EPE around 7.18% and the variances around 26.73%. In comparison, the stratified MCCV can reduce the EPE and variances of the MCCV around 1.58% and 11.85% respectively. The Leave-One-Out (LOO) can lower the EPE around 2.50% but its variances are much higher than the any other CV procedure. The computational time of our cross-validation procedure is just 8.64% of the MCCV, 8.67% of the stratified MCCV and 16.72% of the LOO. Experiments also show that our approach is more beneficial for datasets characterized by relatively small size and large aspect ratio. This makes our approach particularly pertinent when solving bioscience classification problems. Our proposed systematic subsampling technique could be generalized to other machine learning algorithms that involve random subsampling mechanism.

stat.ML

Möbius disjointness for skew products on a circle and a nilmanifold

Let $\mathbb{T}$ be the unit circle and $Γ\backslash G$ the $3$-dimensional Heisenberg nilmanifold. We prove that a class of skew products on $\mathbb{T} \times Γ\backslash G$ are distal, and that the Möbius function is linearly disjoint from these skew products. This verifies the Möbius Disjointness Conjecture of Sarnak.

math.NT

On a certain non-split cubic surface

In this note, we establish an asymptotic formula for the number of rational points of bounded height on the singular cubic surface $$ x_0(x_1^2 + x_2^2)=x_3^3 $$ with a power-saving error term, which verifies the Manin-Peyre conjectures for this surface.

math.NT

On a senary quartic form

We count rational points of bounded height on the non-normal senary quartic hypersurface x 4 = (y 2 1 + $\times$ $\times$ $\times$ + y 2 4)z 2 in the spirit of Manin's conjecture.

math.NT

Manin's conjecture for a class of singular cubic hypersurfaces

Let $n$ be a positive multiple of $4$. We establish an asymptotic formula for the number of rational points of bounded height on singular cubic hypersurfaces $S_n$ defined by $$ x^3=(y_1^2 + \cdots + y_n^2)z . $$ This result is new in two aspects: first, it can be viewed as a modest start on the study of density of rational points on those singular cubic hypersurfaces which are not covered by the classical theorems of Davenport or Heath-Brown; second, it proves Manin's conjecture for singular cubic hypersurfaces $S_n$ defined above.

math.NT

Local Behavior of Arithmetical Functions with Applications to Automorphic L-Functions

We derive a Voronoi-type series approximation for the local weighted mean of an arithmetical function that is associated to Dirichlet series satisfying a functional equation with gamma factors. The series is exploited to study the oscillation frequency with a method of Heath-Brown and Tsang [7]. A by-product is another proof for the well-known result of no element in the Selberg class of degree 0 \textless{} d \textless{} 1. Our major applications include the sign-change problem of the coefficients of automorphic L-functions for GL m , which improves significantly some results of Liu and Wu [14]. The cases of modular forms of half-integral weight and Siegel eigenforms are also considered.

math.NT

The number of coefficients of automorphic $L$-functions for $GL_m$ of same signs

Let $π$ be an irreducible unitary cuspidal representation for $GL_m({\Bbb A}_{\Bbb Q})$, and let $L(s, π)$ be the automorphic $L$-function attached to $π$, which has a Dirichlet series expression in the half-plane $\mbox{Re} s>1$. When $π$ is self-contragredient, all the coefficients in the Dirichlet series expression are real. In this paper we give non-trivial lower bounds for the number of positive and negative coefficients, respectively.

math.NT

The Möbius function and distal flows

We prove that the Möbius function is linearly disjoint from an analytic skew product on the $2$-torus. These flows are distal and can be irregular in the sense that their ergodic averages need not exist for all points. The previous cases for which such disjointness has been proved are all regular. We also establish the linear disjointness of Möbius from various distal homogeneous flows.

math.NT

The Mobius disjointness conjecture for distal flows

We summarize main results in our paper "The Mobius function and distal flows", and give a direct proof with rate of that the Mobius function is disjoint from Furstenberg's irregular system. This will be published in the Proceedings of the Sixth ICCM, held in Taipei in 2013.

math.NT

A Theorem on Analytic Strong Multiplicity One

Let $K$ be an algebraic number field, and $π=\otimesπ_{v}$ an irreducible, automorphic, cuspidal representation of $\GL_{m}(\mathbb{A}_{K})$ with analytic conductor $C(π)$. The theorem on analytic strong multiplicity one established in this note states, essentially, that there exists a positive constant $c$ depending on $\varepsilon>0, m,$ and $K$ only, such that $π$ can be decided completely by its local components $π_{v}$ with norm $N(v)<c\cdot C(π)^{2m+\varepsilon}.$

math.NT