Results 31 to 40 of about 10,599 (72)

Conway groupoids, regular two-graphs and supersimple designs [PDF]

, 2015
A $2-(n,4,\lambda)$ design $(\Omega, \mathcal{B})$ is said to be supersimple if distinct lines intersect in at most two points. From such a design, one can construct a certain subset of Sym$(\Omega)$ called a "Conway groupoid".
Gill, Nick, Gillespie, Neil I., Praeger, Cheryl E., Semeraro, Jason   +3 more
core   +1 more source

Hasse principle for Kummer varieties in the case of generic 2‐torsion

Proceedings of the London Mathematical Society, Volume 131, Issue 1, July 2025.
Abstract Conditional on finiteness of relevant Shafarevich–Tate groups, Harpaz and Skorobogatov used Swinnerton‐Dyer's descent‐fibration method to establish the Hasse principle for Kummer varieties associated to a 2‐covering of a principally polarised abelian variety under certain largeness assumptions on its mod 2 Galois image.
Adam Morgan
wiley   +1 more source

Finite covers of random 3-manifolds

, 2007
A 3-manifold is Haken if it contains a topologically essential surface. The Virtual Haken Conjecture posits that every irreducible 3-manifold with infinite fundamental group has a finite cover which is Haken.
A. Lubotzky, A. Żuk, A.L. Edmonds, A.Y. Ol’shanskiĭ, B. Everitt, B. Weisfeiler, B. Zimmermann, C. Itzykson, C. Livingston, D. Jungreis, D. Zagier, D.M. Jackson, F. Waldhausen, H.M. Hilden, J. Harer, J. Hempel, J. Hempel, J. MacWilliams, L. Carlitz, M. Belolipetsky, M. Gromov, M.E. White, M.J. Evans, M.W. Liebeck, M.W. Liebeck, N.M. Dunfield, Nathan M. Dunfield, P. Diaconis, P. Hall, R. Gilman, R.C. Penner, R.P. Stanley, W. Ledermann, William P. Thurston   +33 more
core   +1 more source

Anticomonotonicity for preference axioms: The natural counterpart to comonotonicity

Theoretical Economics, Volume 20, Issue 3, Page 831-855, July 2025.
Comonotonicity (same variation) of random variables minimizes hedging possibilities and has been widely used, e.g., in Gilboa and Schmeidler's ambiguity models. This paper investigates anticomonotonicity (opposite variation (AC)), the natural counterpart to comonotonicity. It minimizes leveraging rather than hedging possibilities.
Giulio Principi, Peter P. Wakker, Ruodu Wang   +2 more
wiley   +1 more source

Empirical welfare economics

Theoretical Economics, Volume 20, Issue 3, Page 911-939, July 2025.
Welfare economics relies on access to agents' utility functions: we revisit classical questions in welfare economics, assuming access to data on agents' past choices instead of their utilities. Our main result considers the existence of utilities that render a given allocation Pareto optimal.
Christopher P. Chambers, Federico Echenique   +1 more
wiley   +1 more source

The small‐scale limit of magnitude and the one‐point property

Bulletin of the London Mathematical Society, Volume 57, Issue 6, Page 1841-1855, June 2025.
Abstract The magnitude of a metric space is a real‐valued function whose parameter controls the scale of the metric. A metric space is said to have the one‐point property if its magnitude converges to 1 as the space is scaled down to a point. Not every finite metric space has the one‐point property: to date, exactly one example has been found of a ...
Emily Roff, Masahiko Yoshinaga
wiley   +1 more source

Parabolic subgroups in characteristics 2 and 3

Journal of the London Mathematical Society, Volume 111, Issue 6, June 2025.
Abstract This text brings to an end the classification of non‐reduced parabolic subgroups in positive characteristic, especially 2 and 3: they are all obtained as intersections of parabolics having maximal reduced part. We prove this result and deduce a few geometric consequences on rational projective homogeneous varieties.
Matilde Maccan
wiley   +1 more source

Profinite rigidity for free‐by‐cyclic groups with centre

Journal of the London Mathematical Society, Volume 111, Issue 6, June 2025.
Abstract A free‐by‐cyclic group FN⋊ϕZ$F_N\rtimes _\phi \mathbb {Z}$ has non‐trivial centre if and only if [ϕ]$[\phi]$ has finite order in Out(FN)${\rm {Out}}(F_N)$. We establish a profinite rigidity result for such groups: if Γ1$\Gamma _1$ is a free‐by‐cyclic group with non‐trivial centre and Γ2$\Gamma _2$ is a finitely generated free‐by‐cyclic group ...
Martin R. Bridson, Paweł Piwek
wiley   +1 more source

Algebraic relations between solutions of Painlevé equations

Journal of the London Mathematical Society, Volume 111, Issue 6, June 2025.
Abstract In this manuscript, we make major progress classifying algebraic relations between solutions of Painlevé equations. Our main contribution is to establish the algebraic independence of solutions of various pairs of equations in the Painlevé families; for generic coefficients, we show that all algebraic relations between solutions of equations ...
James Freitag, Joel Nagloo
wiley   +1 more source

Simple closed curves, non‐kernel homology and Magnus embedding

Journal of Topology, Volume 18, Issue 2, June 2025.
Abstract We consider the subspace of the homology of a covering space spanned by lifts of simple closed curves. Our main result is the existence of unbranched covers of surfaces where this is a proper subspace. More generally, for a fixed finite solvable quotient of the fundamental group we exhibit a cover whose homology is not generated by the lifts ...
Adam Klukowski
wiley   +1 more source