arXiv subjects

Zihua Wu

Publications and source records attributed to Zihua Wu.

3 recordsLinked to original sources

arXiv2026

Intraday Gas Fee Heterogeneity on Ethereum: Evidence from Operational Firms

Ethereum's EIP-1559 fee mechanism was designed under the assumption of homogeneous, myopic agents responding to a single congestion signal. We examine how this assumption interacts with the heterogeneous demand structure of real-world Ethereum users. Analyzing 62,142 confirmed transactions from seven operational firms across seven industries (January--March 2026), we document significant intraday gas-fee variation: fees peak at hour~12 UTC (7\,AM ET, $\hatβ_{12}=\$0.054$ above the U.S.\ evening baseline, $p<0.001$) and are associated with periods of elevated speculative-arbitrage activity. Operational firms exhibit heterogeneous scheduling responses moderated by transaction deferrability and gas intensity. Residual cost floors, i.e. the gap between observed expenditure and the counterfactual under perfect off-peak scheduling, range from 40.7\% to 92.5\% of actual expenditure, and persist even during the lowest-cost hours ($h\in\{20,21,22,23\}$ UTC, 3--6\,PM ET). We introduce an On-Chain Scheduling Matrix that maps firms to four scheduling regimes as a practical framework for managing gas-fee exposure under the current mechanism.

econ.EM↗

arXiv2026

Boundary-conformal integration for the invariant-imbedding T-matrix method: high-order convergence for faceted particles

The invariant-imbedding T-matrix method (IITM) is a standard tool for light scattering by large, sharply faceted, non-axisymmetric particles (atmospheric ice crystals and mineral dust) where the surface-based extended boundary condition method loses accuracy. Its accuracy is limited by "staircasing": the dielectric contrast of a faceted particle is integrated across boundaries that cut the quadrature grid, so standard quadrature converges at low algebraic order. We show that this non-smoothness has a single geometric origin, the tangencies of the integration sphere to the faces and edges of the particle, which produce jumps, kinks, and half-integer branches according to the tangency type, in all three integration directions. A boundary-conformal scheme removes them using closed-form azimuthal coefficients, panel splitting at the analytically known tangency loci, and a square-root substitution $x \mapsto x_c + t^2$ that absorbs the half-integer branches. For a hexagonal prism the azimuthal integration becomes exact and the zenithal and radial directions recover spectral and fourth-order convergence; because the construction depends only on the contact geometry, it extends to any convex polyhedron, demonstrated on the solid hexagonal bullet (a faceted ice habit with tilted faces). The zenithal crossing is a square-root branch rather than a kink, so the established interval-splitting alone gives only $\mathcal{O}(N^{-3})$, while the radial step removes the half-integer edge branch that caps the Riccati recurrence on faceted particles. The convergence orders are fixed by the local contact geometry and verified size-independent up to $k\,r_{\max} = 20$; what grows with size is the resolution needed to reach each asymptotic regime, not the order.

physics.optics↗

arXiv2026

Context Cartography: Toward Structured Governance of Contextual Space in Large Language Model Systems

The prevailing approach to improving large language model (LLM) reasoning has centered on expanding context windows, implicitly assuming that more tokens yield better performance. However, empirical evidence - including the "lost in the middle" effect and long-distance relational degradation - demonstrates that contextual space exhibits structural gradients, salience asymmetries, and entropy accumulation under transformer architectures. We introduce Context Cartography, a formal framework for the deliberate governance of contextual space. We define a tripartite zonal model partitioning the informational universe into black fog (unobserved), gray fog (stored memory), and the visible field (active reasoning surface), and formalize seven cartographic operators - reconnaissance, selection, simplification, aggregation, projection, displacement, and layering - as transformations governing information transitions between and within zones. The operators are derived from a systematic coverage analysis of all non-trivial zone transformations and are organized by transformation type (what the operator does) and zone scope (where it applies). We ground the framework in the salience geometry of transformer attention, characterizing cartographic operators as necessary compensations for linear prefix memory, append-only state, and entropy accumulation under expanding context. An analysis of four contemporary systems (Claude Code, Letta, MemOS, and OpenViking) provides interpretive evidence that these operators are converging independently across the industry. We derive testable predictions from the framework - including operator-specific ablation hypotheses - and propose a diagnostic benchmark for empirical validation.

cs.AI↗