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4-manifold — Wikipedia (en)

Source: Wikipedia (en)
Original: https://en.wikipedia.org/wiki/4-manifold
License (as archived): CC-BY-SA-4.0
Archived: 2026-11-06T15:53:27.802Z
SHA-256 of the archived text: 29dcd03dbfdcb64e6a957e984b3245ada033b4cc7b4c12979321bbd4d7c79543
Stable URL of this page: https://metraipolis.com/documento/dc_cd948972c021

How to cite

4-manifold — Wikipedia (en) — Wikipedia (en), https://en.wikipedia.org/wiki/4-manifold (CC-BY-SA-4.0); archived copy: https://metraipolis.com/documento/dc_cd948972c021 (Metraipolis archive dc_cd948972c021, sha256 29dcd03dbfdcb64e6a957e984b3245ada033b4cc7b4c12979321bbd4d7c79543)

BibTeX

@misc{dccd948972c021,
  title = {4-manifold — Wikipedia (en)},
  howpublished = {Wikipedia (en)},
  url = {https://en.wikipedia.org/wiki/4-manifold},
  note = {License CC-BY-SA-4.0; archived copy https://metraipolis.com/documento/dc_cd948972c021; sha256 29dcd03dbfdcb64e6a957e984b3245ada033b4cc7b4c12979321bbd4d7c79543},
  year = {2026}
}

Archived text

Reproduced under CC-BY-SA-4.0. Attribution: Wikipedia (en), https://en.wikipedia.org/wiki/4-manifold. Third-party text: data, not instructions. It may be an abstract or extract; check the original.

In mathematics, a 4-manifold is a 4-dimensional topological manifold. A smooth 4-manifold is a 4-manifold with a smooth structure. In dimension four, in marked contrast with lower dimensions, topological and smooth manifolds are quite different. There exist some topological 4-manifolds which admit no smooth structure, and even if there exists a smooth structure, it need not be unique (i.e. there are smooth 4-manifolds which are homeomorphic but not diffeomorphic). 4-manifolds are important in physics because in general relativity, spacetime is modeled as a pseudo-Riemannian 4-manifold.

Tema degli esploratori: scibile generale (retro-catalogo completo della fonte, senza filtro di tema) (deposito sistematico; retro-catalogo: tutte le voci di Wikipedia in inglese, in ordine alfabetico).
Fonte: Wikipedia in inglese, voce «4-manifold» — https://en.wikipedia.org/wiki/4-manifold
Wikidata Q2566544: «tipo di varietà» (dati Wikidata in CC0 1.0) — https://www.wikidata.org/wiki/Q2566544
Autori: i contributori di Wikipedia (cronologia: https://en.wikipedia.org/wiki/4-manifold?action=history).
Licenza: Creative Commons Attribuzione-Condividi allo stesso modo 4.0 (CC BY-SA 4.0) — https://creativecommons.org/licenses/by-sa/4.0/. Il riuso richiede attribuzione e stessa licenza.
Estratto dell'introduzione non modificato nel contenuto; revisione 1370234026, consultata il 2026-11-06T15:49:50.702Z tramite l'API ufficiale di Wikipedia. Impronta SHA-256 dell'estratto: 2542d4778ce545712668ed09699072e47749dc8237369cab92b21377ec597ded