Timeline for Suspension of an excisive pair
Current License: CC BY-SA 3.0
10 events
| when toggle format | what | by | license | comment | |
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| Jan 15, 2012 at 15:44 | comment | added | old account | Oh boy, you are of course absolutely right. | |
| Jan 10, 2012 at 14:05 | comment | added | Tom Goodwillie | And if you switch over to considering square diagrams then it's easy to see that when one such square is excisive (i.e. induces isomorphisms between homology of opposite sides) then the square of suspensions is excisive as well. | |
| Jan 10, 2012 at 14:02 | comment | added | Tom Goodwillie | As Karol Szumilo suggested in his answer, the "right" question is about square diagrams rather than triads. As further evidence for this, I point out that the suspension of the intersection is not actually the same as the intersection of the suspensions. In fact, it is not clear what one would mean by intersection of the suspensions of two subspaces, since the suspension of a subspace is not always a subspace of the suspension. The suspension of an open interval is not metrizable. | |
| Jan 10, 2012 at 12:41 | comment | added | old account | Does that warrant an entirely new thread? Or should I simply edit my question above? | |
| Jan 10, 2012 at 12:41 | comment | added | old account | Off to embarrass myself some more: Of course you are absolutely correct in that I should have asked the second question (I used the forbidden distributive law S(X−U)=SX−SU when formulating the question here.) I accepted your answer; it nicely answers the question I posed. However I'm still at loss with the correctly formulated question... The 'interiors cover' property is again lost at the poles. I can clearly see the statement for example in the case of a CW-pair, but in general? | |
| Jan 10, 2012 at 10:23 | vote | accept | old account | ||
| Jan 5, 2012 at 19:41 | comment | added | Karol Szumiło | My answer is essentially the same as yours. (I didn't try to "improve" it, I'm just a slow typer.) | |
| Jan 5, 2012 at 19:28 | history | edited | Tom Goodwillie | CC BY-SA 3.0 |
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| Jan 5, 2012 at 19:21 | history | edited | Tom Goodwillie | CC BY-SA 3.0 |
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| Jan 5, 2012 at 19:12 | history | answered | Tom Goodwillie | CC BY-SA 3.0 |