Timeline for Units of MO and MU
Current License: CC BY-SA 3.0
6 events
| when toggle format | what | by | license | comment | |
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| Dec 15, 2016 at 5:26 | comment | added | Tyler Lawson | Dear Ulrich, did you ever find any useful information about these unit groups? | |
| Apr 16, 2014 at 21:10 | vote | accept | Ulrich Pennig | ||
| Mar 28, 2013 at 18:41 | comment | added | Suvrit | Given the title, I thought you were gonna discuss "units of Mathoverflow and Mathunderflow (aka math.SE) ---- but this turned out to be bait-and-switch ;-) | |
| Mar 28, 2013 at 12:59 | answer | added | Peter May | timeline score: 13 | |
| Mar 28, 2013 at 12:41 | comment | added | Tyler Lawson |
One comment is that if $S$ is the sphere spectrum there is a map $U\to GL_1(S)$ (resp. $O \t GL_1(S)$) and the description of MU explicitly makes the composite $U\to GL_1(S) \to GL_1(MU)$ nullhomotopic as a map of infinite loop spaces (similarly for $MO$). Another is that even though $MO$ is equivalent to a product of Eilenberg-Mac Lane objects, $GL_1(MO)$ is (as an infinite loop space) not. $GL_1$ is tough, and a good chunk of literature in orientation theory (much by Peter May) is devoted to determining information about it.
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| Mar 28, 2013 at 9:14 | history | asked | Ulrich Pennig | CC BY-SA 3.0 |