Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options not deleted user 171227

Questions related to permutations, bijections from a finite (or sometimes infinite) set to itself.

3 votes

Conceptual reason why the sign of a permutation is well-defined?

It is related to the Steenrod operation $\mathrm{Sq}^2$ vanishing in the cohomology of the sphere spectrum. This vanishing is witnessed by a spectrum map $\sigma: S \to E$, where $E$ is the fiber of a …
user171227's user avatar