Timeline for The second homotopy group of a simple CW-complex
Current License: CC BY-SA 3.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Dec 16, 2011 at 16:13 | vote | accept | Julien Marché | ||
| Dec 16, 2011 at 13:09 | comment | added | Benjamin Steinberg | @Julien, if you click the check mark next to the answer it accepts Agol's answer as the official one. | |
| Dec 16, 2011 at 12:24 | comment | added | Julien Marché | Well thank you very much, this is a very nice answer! | |
| Dec 16, 2011 at 5:47 | comment | added | Benjamin Steinberg | Just to make this nice answer explicit, let $w(x,y)$ be the word $xyxy^2\cdots xy^{100}$. Then the presentation $$\langle a,b\mid w(a,b), w(b,a), w(ab,ba)\rangle$$ satisfies $C'(1/6)$ if I am not mistaken and so has a presentation complex with 1 0-cell, 2 1-cells, 3 2-cells and nothing more with trivial $\pi_2$ by the result cited in the Wiki article. | |
| Dec 16, 2011 at 1:51 | history | answered | Ian Agol | CC BY-SA 3.0 |