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Xiumei Li

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8works
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8 publications

preprint2026arXiv

TAFA-GSGC: Group-wise Scalable Point Cloud Geometry Compression with Progressive Residual Refinement

Scalable compression is essential for bandwidth-adaptive transmission, yet most learned codecs are optimized for a fixed rate-distortion point, making rate adaptation costly due to re-encoding or maintaining multiple bitstreams. In this work, we propose TAFA-GSGC, a scalable learned point cloud geometry codec that enables multi-quality decoding from a single bitstream and a single trained model. TAFA-GSGC combines layered residual refinement with channel-group entropy coding, and introduces a Target-Aligned Feature Aggregation module to reduce cross-layer redundancy in enhancement residuals. Our framework supports up to 9 decodable quality levels with monotonic quality improvement as more subbitstreams are received, while maintaining strong compression efficiency. Compared with the PCGCv2 baseline, TAFA-GSGC demonstrates improved RD performance, achieving average BD-rate reductions of 4.99% and 5.92% in terms of D1-PSNR and D2-PSNR, respectively.

preprint2020arXiv

A proof of Sondow's conjecture on the Smarandache function

The Smarandache function of a positive integer nn, denoted by S(n)S(n), is defined to be the smallest positive integer jj such that nn divides the factorial j!j!. In this note, we prove that for any fixed number k>1k > 1, the inequality nk<S(n)!n^k < S(n)! holds for almost all positive integers nn. This confirms Sondow's conjecture which asserts that the inequality n2<S(n)!n^2 < S(n)! holds for almost all positive integers nn.

preprint2020arXiv

Polynomial analogue of the Smarandache function

In the integer case, the Smarandache function of a positive integer nn is defined to be the smallest positive integer kk such that nn divides the factorial k!k!. In this paper, we first define a natural order for polynomials in Fq[t]\mathbb{F}_q[t] over a finite field Fq\mathbb{F}_q and then define the Smarandache function of a non-zero polynomial f∈Fq[t]f \in \mathbb{F}_q[t], denoted by S(f)S(f), to be the smallest polynomial gg such that ff divides the Carlitz factorial of gg. In particular, we establish an analogue of a problem of Erd{\H o}s, which implies that for almost all polynomials ff, S(f)=tdS(f)=t^d, where dd is the maximal degree of the irreducible factors of ff.

preprint2020arXiv

Weight distributions of several families of 3-weight binary linear codes

The linear codes with a few weights have been applied widely in combinatorial designs, secret sharing, association schemes, authentication codes and strongly regular graphs. In this paper, we first correct an erroneous result about the exponential sum ∑x∈F2eχ1(ax2α+1+bx).\sum_{x\in \mathbb{F}_{2^{e}}}χ_1\left(ax^{2^α+1}+bx\right). Then, using the above exponential sum, we construct several families of binary linear codes of 33-weight and determine their weight distributions. Moreover, Most of them can be used in secret sharing schemes.

preprint2020arXiv

Weight hierarchies and weight distributions of a familiy of pp-ary linear codes

The weight distribution and weight hierarchy of linear codes are two important research topics in coding theory. In this paper, by choosing proper defining sets from inhomogeneous quadratic functions over Fq2,\mathbb{F}_{q}^{2}, we construct a family of 33-weight pp-ary linear codes and determine their weight distributions and weight hierarchies. Most of the codes can be used in secret sharing schemes.

preprint2020arXiv

Weight hierarchies of a family of linear codes associated with degenerate quadratic forms

We restrict a degenerate quadratic form ff over a finite field of odd characteristic to subspaces. Thus, a quotient space related to ff is introduced. Then we get a non-degenerate quadratic form induced by ff over the quotient space. Some related results on the subspaces and quotient space are obtained. Based on this, we solve the weight hierarchies of a family of linear codes related to f.f.

preprint2013arXiv

Factoring integer using elliptic curves over rational number field Q\mathbb{Q}

For the integer D=pq D=pq of the product of two distinct odd primes, we construct an elliptic curve E2rD:y2=x3−2rDxE_{2rD}:y^2=x^3-2rDx over Q\mathbb Q, where rr is a parameter dependent on the classes of pp and qq modulo 8, and show, under the parity conjecture, that the elliptic curve has rank one and vp(x([k]Q))≠vq(x([k]Q))v_p(x([k]Q))\not=v_q(x([k]Q)) for odd kk and a generator QQ of the free part of E2rD(Q)E_{2rD}(\mathbb Q). Thus we can recover pp and qq from the data DD and x([k]Q)) x([k]Q)). Furthermore, under the Generalized Riemann hypothesis, we prove that one can take r<clog⁡4Dr<c\log^4D such that the elliptic curve E2rDE_{2rD} has these properties, where cc is an absolute constant.

preprint2012arXiv

On the Selmer groups and Mordell-Weil groups of elliptic curves y2=x(x±p)(x±q) y^{2} = x (x \pm p) (x \pm q) over imaginary quadratic number fields of class number one

Let p p and q q be odd prime numbers with q−p=2, q - p = 2, the φ−φ-Selmer groups, Shafarevich-Tate groups (φ− φ- and 2− 2-part) and their dual ones as well the Mordell-Weil groups of elliptic curves y2=x(x±p)(x±q) y^{2} = x (x \pm p) (x \pm q) over imaginary quadratic number fields of class number one are determined explicitly in many cases.

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