A Proof of the Continued Fraction Identity π/4=Kn=1((n1)2/(2n1))-\pi/4 = {\rm K}_{n=1}^{\infty}\bigl((n-1)^2\,/\,{-(2n-1)}\bigr)

This paper provides a self-contained analytic proof of the continued fraction identity π/4=Kn=1((n1)2/(2n1))-\pi/4 = {\rm K}_{n=1}^{\infty}\bigl((n-1)^2\,/\,{-(2n-1)}\bigr) by transforming the classical Gauss continued fraction for arctan(z)\arctan(z) evaluated at z=1z=-1 and demonstrates its super-exponential convergence advantage over the Gregory–Leibniz series.

Chao Wang2026-03-10🔢 math

Hematopoiesis as a continuum: from stochastic compartmental model to hydrodynamic limit

This paper establishes a hydrodynamic limit for a multiscale stochastic compartmental model of hematopoiesis, proving that the dynamics of stem, immature, and mature cells converge to a deterministic system of partial differential equations with boundary conditions as the number of immature compartments approaches infinity.

Vincent Bansaye (CMAP, MERGE), Ana Fernández Baranda (CMAP, MERGE), Stéphane Giraudier (AP-HP), Sylvie Méléard (MERGE, CMAP)2026-03-10🔢 math

Rigidity of Koebe Polyhedra and Inversive Distance Circle Packings

This paper establishes the global rigidity of hyperbolic inversive distance circle packings on the 2-sphere, and equivalently of Koebe polyhedra in the Beltrami-Klein model, under mild assumptions on vertex links, thereby generalizing previous rigidity results and the uniqueness part of the Koebe-Andreev-Thurston Theorem to cases where adjacent circles need not touch.

John C. Bowers, Philip L. Bowers, Carl O. R. Lutz2026-03-10🔢 math

Reverse square function estimates for degenerate curves and its applications

This paper establishes L4L^4 reverse square function estimates for functions with Fourier support near degenerate curves {(ξ,ξa)}\{(\xi,\xi^a)\} (for a1a \neq 1), which are then applied to derive sharp L4L^4 Strichartz estimates for fractional Schrödinger equations on the one-dimensional torus and new local smoothing estimates in modulation spaces.

Aleksandar Bulj, Kotaro Inami, Shobu Shiraki2026-03-10🔢 math