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Yong Yang

Publications and source records attributed to Yong Yang.

At least 19 recordsLinked to original sources
arXiv2026

See you again: an $80^\circ$ NGC~5466 stellar stream and its constraints on the Galactic dark halo mass

Using \textit{Gaia} Data Release 3 combined with Dark Energy Spectroscopic Instrument Legacy Imaging Survey Data Release 9 and Panoramic Survey Telescope and Rapid Response System Data Release 2, we apply a modified matched filter method to obtain a weighted stellar map in the surrounding of the globular cluster NGC~5466. Our results support that the tidal stream of NGC~5466 extends around $80^\circ$ on the sky, and the leading tail seemingly exhibits an upward deviation in the range of $180^\circ \lesssim α\lesssim 190^\circ$, which supports previous claim that the Large Magellanic Cloud (LMC) may have caused dynamical perturbations to the stream. Based on the 308 highly-weighted member candidates of the NGC~5466 stream, we try to measure the mass distribution of the Milky Way dark matter halo along with the mass of LMC. By comparing the observed stream candidate members to a series of model streams generated under different potential parameters, we obtain the posterior distributions of the parameters: the circular velocity at the solar radius $V_{\rm c} = 239.56^{+1.46}_{-1.44}\ \mathrm{km\ s^{-1}}$, the density flattening of the halo $q = 1.08^{+0.07}_{-0.07}$, the scale radius of the halo density profile $r_s = 12.97^{+3.02}_{-2.18}\ \mathrm{kpc}$ and the total mass of the LMC $M_{\rm LMC} = 9.63^{+1.89}_{-2.00}\times 10^{10}$ $\mathrm{M_\odot}$. The enclosed mass of the Milky Way within the stream apocenter radius of $\sim$ 50 kpc is calculated as $M_{\rm MW}(<50~\mathrm{kpc}) = 4.59^{+0.48}_{-0.37} \times 10^{11}$ $\mathrm{M_\odot}$.

astro-ph.GA↗
arXiv2026

Abelian quotients and orbit sizes for subgroups of linear groups

Keller and Yang formulated two conjectures relating abelian quotients of subgroups of finite linear groups to largest orbit sizes. After counterexamples were found to the original conjectures, two revised versions were proposed. We prove both revised conjectures for every finite group $G$ satisfying $F(G)=F^*(G)$. We also extend a regular-orbit theorem for nilpotent subgroups to completely reducible modules of mixed characteristic under the same hypothesis.

math.GR↗
arXiv2026

Orbits of $p$-Nilpotent Group Actions for Small Primes

Let $G$ be a finite solvable group and $V$ be a faithful completely reducible $G$-module. We improve previous bounds for the sizes of defect groups of blocks of solvable groups through an improved bound on vector stabilizers of $p$-nilpotent groups. Specifically, if $G$ is 2-nilpotent and $2 \nmid |V|$, then there exists $v \in V$ such that $\mathbf{C}_G(v) \leq \mathbf{F}_4(G)$. Similarly, if $G$ is 3-nilpotent and $3 \nmid |V|$, then there exists $v \in V$ such that $\mathbf{C}_G(v) \leq \mathbf{F}_5(G)$. Using these results, we conclude that $d(B) \leq \lfloor \frac{9n}{10} \rfloor$ when $O_p(G) = 1$ for $p = 2$ and $d(B) \leq \lfloor \frac{19n}{21} \rfloor$ when $O_p(G) = 1$ for $p = 3$.

math.GR↗
arXiv2026

On Finite Groups with Element Order Set of Width 3

We study finite groups in which every element order is divisible by at most three distinct primes. We determine the possible nonabelian composition factors, prove that a nonabelian simple group with this property has at most $15$ prime divisors in its order, and deduce that $ρ(G)\leq192$ for every finite group $G$ with $α(G)\leq3$.

math.GR↗
arXiv2026

Compile the Table: Query-Calibrated Operator Compression for Tabular In-Context Learning

Tabular in-context learning (ICL) has emerged as a training-free and accurate paradigm for tabular prediction, but current approaches to compressing its in-context examples face an accuracy-throughput tradeoff: fixed subsets can sacrifice accuracy, while query-specific retrieval limits cache reuse and batching across queries, reducing throughput. We propose QCOC (Query-Calibrated Operator Compression), which exploits the exchangeability and repeated use of in-context examples by compiling their full KV cache once into compact memory shared across subsequent queries. Instead of retaining raw examples, QCOC clusters their states into joint-KV prototypes, preserves per-cluster multiplicities and the original example count, and calibrates prototype values against attention query vectors produced by the in-context examples through an anchored closed-form solution. Prototype compression drives the speedup, while value fitting helps preserve accuracy. On 64 held-out OpenML-CC18 datasets, QCOC achieves the highest mean accuracy among the compared compression and retrieval methods at both retained counts. Across 12 configurations on seven long tables, it ranks first among compressed methods in ten and averages 0.23 percentage points below full context. Compressing 8,192 in-context examples to 512 memory slots yields a 10.5x cache compression ratio; excluding one-time compilation, in a single-core CPU online-serving comparison over 1,000 queries, QCOC is up to 508x faster than dynamic retrieval baselines and 1.98x faster than full-context inference. These results show that QCOC enables compact-memory reuse and efficient inference across queries while retaining accuracy close to full context.

cs.LG↗
arXiv2026

SANet: Selective Attention Network for Infrared Small Target Detection

Infrared small target detection aims to accurately identify and locate dim targets in complex backgrounds and supports applications such as maritime surveillance and military search and rescue. However, the small size and weak contrast of infrared targets make it difficult to balance detection accuracy and false alarms. This paper proposes a selective attention network (SANet) for infrared small target detection. A dual-path semantic-aware module combines standard and pinwheel-shaped convolutions to preserve local spatial consistency and capture broader contextual information. Spatial and channel attention further refine the features and improve target-background discrimination. To address the limitations of static skip connections in U-Net, a selective attention fusion module adaptively integrates features across scales using spatially varying weights. It selectively enhances salient regions and improves discrimination between true targets and false alarms. Experiments on three public benchmarks, NUAA-SIRST, IRSTD-1K, and NUDT-SIRST, show that SANet achieves competitive performance in intersection over union (IoU), normalized IoU, detection probability, and false alarm rate. Its IoU exceeds that of the second-best method by 1.93, 4.32, and 2.21 percentage points, respectively. These results support the effectiveness of SANet in dim-target perception, discriminative feature representation, and background suppression.

cs.CV↗
arXiv2026

X2SBench: an open benchmark for evaluating crystal structure determination from powder diffraction

Progress towards practical powder X-ray diffraction (PXRD) structure determination requires evaluation beyond small crystals and idealized patterns. X2SBench combines 152,587 simulated structure-pattern pairs with 591 curated measurements, extending evaluation to larger cells, lower-symmetry structures and diverse compositions. Fixed splits, defined inputs and common structural metrics support comparisons by crystal system, atom count and element count. Joint stratification locates weaknesses within these groups. On 558 paired targets, an X2SBench-fine-tuned model improves recovery from simulated patterns but loses accuracy on measured inputs, revealing a gap in experimental transfer. Background subtraction and smoothing improve recovery for one tested checkpoint, while augmentation and reference-lattice comparisons identify further opportunities for measurement adaptation and reliable cell estimation. An open platform provides data access and standardized result submission, establishing a shared basis for community evaluation and progress towards practical PXRD analysis.

cond-mat.mtrl-sci↗
arXiv2026

Zeros and Roots of Unity for Characters of Solvable Groups

We prove Miller's conjectured bound for solvable groups: if $G$ is a finite solvable group and $χ\in\Irr(G)$, then $χ(g)$ is zero or a root of unity for at least half of the elements $g\in G$. We also prove the same bound for monomial irreducible characters of arbitrary finite groups.

math.GR↗
arXiv2026

On Intersections of System Normalizers

We give a negative answer to Problem 17.39 of the Kourovka Notebook. For every odd prime power $q$ and every $m\geq1$, we construct a finite metabelian group $G_{m,q}$ with $Z_\infty(G_{m,q})=1$ and $|Φ(G_{m,q})|=q$ for which the least number of system normalizers with trivial intersection is $m+1$. Thus the number is unbounded even when the order of the Frattini subgroup is fixed.

math.GR↗
arXiv2026

An order automorphism of a Dlab group not induced by conjugation

Let $G=D_{\langle2\rangle}([0,1])$ be equipped with either of its two Dlab orders. There exists an order automorphism $α$ of $G$ such that, for every rank-one subgroup $H\leq\mathbb R_{>0}^{\times}$, every one of the six corresponding Dlab groups $A$ listed below, equipped with any of its linear orders, every order-preserving embedding $e:G\hookrightarrow A$, and every $u\in A$, there exists $f\in G$ such that $e(α(f))\neq u^{-1}e(f)u$.

math.GR↗
arXiv2026

IntraGuard: Committee-Side Defenses Against Review Outsourcing to Commercial Chatbots

LLMs become increasingly capable, editorial boards and program committees are growing concerned about reviewers who fully outsource peer review to commercial chatbots. This concern stems from prior findings that current chatbots lack the independent critical thinking and depth of reasoning required to assess scientific novelty. One promising direction for mitigating this concern is to embed hidden instructions into manuscripts that disrupt or alter chatbot-generated reviews. However, existing methods remain intuitive and fragile, as they typically rely on homogeneous payloads injected in an inter-stream manner, rendering them susceptible to sanitization or neutralization. More broadly, the community still lacks a systematic formulation of this threat and a principled defense framework. In this paper, we identify End-to-End Review Outsourcing as an emerging threat and propose IntraGuard, a black-box, venue-agnostic defense framework grounded in the structural--visual decoupling inherent to the PDF. Designed for committee-side deployment, IntraGuard supports both explicit strategies that trigger refusal or warning signals, and implicit strategies that embed predefined textual markers into the generated review. These strategies can be deployed via any of three intra-stream injection mechanisms, each of which seamlessly embeds heterogeneous defensive text objects within the PDF's underlying structure without altering its visual presentation. Extensive evaluations (over 17,844 cases) across 7 real-world commercial chatbot settings and 12 venues spanning diverse disciplines show that IntraGuard achieves a defense success rate of up to 84%, while preserving peer-review invariance for human reviewers. We further evaluate 11 adaptive attacks spanning manuscript sanitization and instruction interference, and discuss the implications of constructing ensemble defenses.

cs.CR↗
arXiv2026

Search for neutrinoless quadruple beta decay of $^{136}$Xe in PandaX-4T detector

The observation of neutrinoless quadruple beta decay (0$ν$4$β$) in the absence of neutrinoless double beta decay (0$ν$2$β$) has been argued to provide a strong indication that neutrinos are Dirac particles. We report a search for 0$ν$4$β$ decay of $^{136}\text{Xe}$ using a total $^{136}\text{Xe}$ exposure of 148.4 kg$\cdot$yr, collected during the commissioning and the first science runs of the PandaX-4T experiment. No significant excess of events over the background is observed. A lower limit on the 0$ν$4$β$ decay half-life of $^{136}\text{Xe}$ is set at 6.01 x $10^{24}$ yr at the 90% confidence level. This result establishes the most stringent constraint on this process in xenon, demonstrating the unique capability of the PandaX-4T detector in probing lepton number violation and shedding light on the fundamental nature of neutrinos.

nucl-ex↗
arXiv2026

Safety in Self-Evolving Agents: A Survey

Large language models (LLMs) exhibit strong general capabilities, yet their parameters typically remain fixed after deployment, limiting learning from new interactions. In open-ended environments, this motivates self-evolving agents that continually update reusable state-including model parameters, memories, tool definitions, skills, and workflows-from data, feedback, and accumulated experience. This shift changes the safety problem: once experience becomes reusable state, past events become future causes, and information harmless in one context may later influence decisions with greater persistence, authority, or scope. Self-evolving agent safety therefore asks not only whether a response is aligned or an action authorized, but whether safety properties survive the accumulation, generalization, and cross-context reuse of locally useful experience. We introduce SAVER, a transition-centered framework in which Substrate locates reusable influence, Adaptation captures how it changes, Violation identifies compromised safety attributes, Exposure marks where failures become observable, and Response assesses containment, repair, or revocation. Our survey reveals that failures need not originate from harmful information: legitimate state can become unsafe when adaptation expands its persistence, authority, or scope beyond the conditions under which it was valid. Existing work provides comparatively strong evidence for admission, retrieval, activation, exposure, and local containment, but much less for descendant repair and evaluation after adaptation resumes. We therefore argue for longitudinal evaluation that traces unsafe influence to its originating transition, verifies repair across descendants, and tests whether it can re-emerge under continued evolution.

cs.CR↗
arXiv2026

A Huppert-type $ρ^*$--$σ^*$ theorem for sub-class sizes

For a finite group $G$, let $ρ^{*}(G)$ be the set of primes dividing some sub-class size of $G$, and let $σ^{*}(G)$ be the maximum number of distinct prime divisors of a sub-class size. Motivated by the conjugacy-class version of Huppert's $ρ$--$σ$ problem, we prove that \[ |ρ^{*}(G)|<2σ^{*}(G) \] for every finite nonnilpotent group $G$. This answers \cite[Remark~5.3]{QY} and extends to arbitrary finite nonnilpotent groups the coefficient-$2$ bound proved in \cite[Theorem~1.7]{QY} for solvable nonnilpotent groups. The coefficient $2$ is best possible. The proof does not use the classification of finite simple groups.

math.GR↗