MathOverflow

Math Overflow. Q&A for professional mathematicians.

Read Mathoverflow.net news digest here: view the latest Math Overflow articles and content updates right away or get to their most visited pages. Mathoverflow.net belongs to a group of fairly successful websites, with more than 458K visitors from all over the world monthly. It seems that Math Overflow content is notably popular in USA, as 32.4% of all users (148K visits per month) come from this country. We haven’t detected security issues or inappropriate content on Mathoverflow.net and thus you can safely use it. Mathoverflow.net is hosted with Stack Exchange, Inc. (United States) and its basic language is English.

  • Content verdict: Safe
  • Website availability: Live
  • English language flagLanguage: English
  • Last check:
  • 15 260

    Visitors daily
  • 54 936

    Pageviews daily
  • 6

    Google PR
  • 20 923

    Alexa rank

Mathoverflow.net news digest

  • 1 year

    Continuous functions on HLS groupoids

    I am reading a paper about property (T) for groupoids: Topological property (T) for groupoids. In section 4.4 they discuss the HLS groupoids which I describe define here.
    Let $\Gamma$ be a discrete group and $(N_k)_{k \in \mathbb N}$ a decreasing sequence of normal subgroups of finite index. Let $\Gamma_k := \Gamma/N_k$ and denote $q_k: \Gamma \rightarrow \Gamma_k$ the quotient homomorphism. If we let $\overline{\mathbb...

  • 5 years

    A robust version of Harper's theorem

    Let $S$ be a subset of $\{0,1\}^n$ with cardinality $k$.
    Denote by $\Gamma_r(S)$ the union of all Hamming balls of radius $r$ centered at points of $S$.
    Harper's theorem states that $|\Gamma_r(S)|$ is minimized when $S$ is a Hamming ball (see also this question)....

  • 0 days

    Why are polynomials of degree 24 with 20 real roots hard to find?

    The ongoing SAIR Inverse Galois Problem challenge asks teams to find, for each pair $(G,r)$ consisting of a transitive subgroup $G$ of $S_{24}$ and a number $r$ such that $G$ contains an involution with $r$ fixed points, an irreducible polynomial over...

  • 19 days

    Question about the statement of Geometric Langlands

    I have started to read about Geometric Langlands from Frenkel's book
    https://arxiv.org/abs/hep-th/0512172.
    As said in Theorem $3$ of the book, the Langlands correspondence is stated as follows

Domain history

Web host: Stack Exchange, Inc.
Registrar: GoDaddy.com, LLC
Registrant: Registration Private (Domains By Proxy, LLC)
Updated: May 11, 2026
Expires: July 14, 2026
Created: July 14, 2009

Whois record

Visitor gender

Male

Female

Safety scores

Trustworthiness

Excellent

Child safety

Excellent