Dowker space

Dowker space

A Dowker space is a topological space that is T4 but not countably paracompact.

Equivalences

If X is a normal T1 space (a T4 space), then the following are equivalent:

Dowker conjectured that there were no Dowker spaces, and the conjecture was not resolved until M.E. Rudin constructed one[2] in 1971. Rudin's counterexample is a very large space (of cardinality \aleph_\omega^\omega) and is generally not well-behaved. Zoltán Balogh gave the first ZFC construction[3] of a small (cardinality continuum) example, which was more well-behaved than Rudin's. Using PCF theory, M. Kojman and S. Shelah constructed[4] a Dowker space of cardinality \aleph_{\omega+1}.

References

  1. ^ C.H. Dowker, On countably paracompact spaces, Can. J. Math. 3 (1951) 219-224. Zbl. 0042.41007
  2. ^ M.E. Rudin, A normal space X for which X × I is not normal, Fundam. Math. 73 (1971) 179-186. Zbl. 0224.54019
  3. ^ Z. Balogh, "A small Dowker space in ZFC", Proc. Amer. Math. Soc. 124 (1996) 2555-2560. Zbl. 0876.54016
  4. ^ M. Kojman, S. Shelah: "A ZFC Dowker space in \aleph_{\omega+1}: an application of PCF theory to topology", Proc. Amer. Math. Soc., 126(1998), 2459-2465.

Wikimedia Foundation. 2010.

Игры ⚽ Нужно решить контрольную?

Look at other dictionaries:

  • Clifford Hugh Dowker — (1912–1982) was a topologist known for his work in point set topology and also for his contributions in category theory, sheaf theory and knot theory. Contents 1 Biography 2 Work 3 References 4 …   Wikipedia

  • List of mathematics articles (D) — NOTOC D D distribution D module D D Agostino s K squared test D Alembert Euler condition D Alembert operator D Alembert s formula D Alembert s paradox D Alembert s principle Dagger category Dagger compact category Dagger symmetric monoidal… …   Wikipedia

  • Zoltán Tibor Balogh — Zoltán Zoli Tibor Balogh (December 7, 1953 – June 19, 2002) was a Hungarian born mathematician, specializing in set theoretic topology. His father, Tibor Balogh, was also a mathematician.His best known results concerned solutions to problems… …   Wikipedia

  • Mary Ellen Rudin — (born December 7, 1924, Hillsboro, Texas) is an American mathematician. Born Mary Ellen Estill, she attended the University of Texas, completing her B.A. in 1944 and her Ph.D. in 1949, under Robert Lee Moore.[1] In 1953, she married the… …   Wikipedia

  • Knot theory — A three dimensional depiction of a thickened trefoil knot, the simplest non trivial knot …   Wikipedia

  • Causal set theory bibliography — Main article: Causal Sets This Causal Set Theory Bibliography is intended to aid causal set research. It gathers together academic papers, books, talks and PhD theses related to causal set theory and is intended to help readers find references… …   Wikipedia

  • Ditmar Award results — Main article: Ditmar Award The Ditmar Award is Australia s oldest and best known science fiction, fantasy and horror award, presented annually at the Australian NatCon since 1969. The historical nominations and results (listed in boldface) of the …   Wikipedia

  • Ball (mathematics) — N ball redirects here. For the video game, see N ball (game). A ball is the inside of a sphere In mathematics, a ball is the space inside a sphere. It may be a closed ball (including the boundary points) or an open ball (excluding them). These… …   Wikipedia

  • Stephen Hawking — Infobox Scientist box width = 250x name = Stephen Hawking image size = 200px caption = NASA StarChild image of Stephen Hawking birth date = birth date and age|df=yes|1942|01|8 birth place = Oxford, England death date = death place = residence =… …   Wikipedia

  • John von Neumann — Von Neumann redirects here. For other uses, see Von Neumann (disambiguation). The native form of this personal name is Neumann János. This article uses the Western name order. John von Neumann …   Wikipedia

Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”