Topospaces:Error log

Did you find something that looks like an error (or possible error) to you? Report the error quickly here (anonymous, does not require login, but you can optionally provide an email ID to be notified of the fix).

We have just started logging errors. On this page, you will find information about all errors that persisted on the site for more than one month on any page. Note: This applies only to errors that were not fixed by December 18, 2011. Errors fixed before then are not being logged on this page.

Page	Error description	Version where it was introduced	Version where it was corrected	Why error? Why not caught? ("I" refers to Vipul)
Metrizable implies monotonically normal	Had wrong direction of inequality ($\leq$ when it should have been $\geq$)		July 6, 2019	carelessness
Space of path components	Incorrect statement that induced multiplication on space of path components gives a topological monoid structure; in fact it need not be continuous	December 20, 2010	July 6, 2019	genuine conceptual confusion
Compact times paracompact implies paracompact	General sloppiness in proof, missed some inclusion conditions		June 3, 2017	Additional conditions were implicit when reading; carelessness in review
Homotopy type of connected sum depends on choice of gluing map	Excluded one relation from cohomology ring description	July 29, 2011	December 15, 2016	Ignored interaction term in analysis
Connected sum of two complex projective planes with opposite orientation	Excluded one relation from cohomology ring description	July 29, 2011	December 15, 2016	Ignored interaction term in analysis
Connected sum of two complex projective planes with same orientation	Excluded one relation from cohomology ring description	July 29, 2011	December 13, 2016	Ignored interaction term in analysis
Paracompact Hausdorff implies normal	Didn't say "disjoint closed subsets" in "To prove"		November 21, 2016	carelessness, insufficient review
Paracompact Hausdorff implies normal	Used $U$ instead of $A$ at one place		May 30, 2016	Didn't proofread carefully
Locally operator	Incorrect statement that $p$ implies locally $p$		May 30, 2016	There are many different meanings of "locally" and many are equivalent for some kinds of properties
Quaternionic projective space has fixed-point property iff it has even quaternionic dimension	incorrect statement		May 30, 2016
Locally path-connected space	Incorrectly said it is obtained by applying the locally operator		May 30, 2016	Multiple definitions of "locally" floating around
Locally contractible space	incorrectly stated contractible space to be stronger		May 30, 2016	carelessness, insufficient review
Homotopy of spheres, homotopy of real projective space, homotopy of complex projective space	Stated that some groups are $\mathbb {Z}$ when all we know is that sometimes they are infinite.		April 2016	Difficult topic, basically just guesswork/poor sourcing
Noetherian space	copy/pasted one definition to another		November 15, 2015	carelessness, insufficient review
Hausdorffization	provided incorrect definition that seemed prima facie plausible		November 15, 2015	genuine knowledge gap, common confusion
2-torus	typo: wrote cohomology instead of homology		May 15, 2015	careless error; didn't proofread enough
Jointly continuous map	typo: wrote that slice topology is finer than slice topology, meant it is finer than product topology	December 20, 2010	May 15, 2015	Typo, didn't proofread, and didn't revisit the page.
Path-connected implies connected	Wrote "open" instead of "nonempty"	December 25, 2009	December 19, 2014	Typo, didn't review the page carefully enough
Manifold	mistakenly wrote "equivalent" for a bunch of conditions all of which need to be satisfied.		November 2, 2014	Typo, didn't proofread.
Double mapping cylinder	wrote $Y\to Z$ instead of $X\to Z$.	November 2, 2007	February 11, 2014	Typo, didn't proofread.
Weak homotopy equivalence of topological spaces	provided incorrect definition in the form of "induces isomorphisms on $\pi _{1}$ and on homology"		November 18, 2013	genuine knowledge gap, common confusion.