Timeline for How to prove that a subset in a vector space is an indicatrix?
Current License: CC BY-SA 3.0
13 events
| when toggle format | what | by | license | comment | |
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| Jun 29, 2017 at 17:29 | comment | added | Majid | @BenMcKay Your answer is definitely an answer to the previous version of my question. Thanks. | |
| Jun 29, 2017 at 17:25 | vote | accept | Majid | ||
| Jun 29, 2017 at 17:25 | |||||
| Jun 29, 2017 at 17:24 | vote | accept | Majid | ||
| Jun 29, 2017 at 17:24 | |||||
| Jun 20, 2017 at 19:00 | history | edited | Ben McKay | CC BY-SA 3.0 |
explained why this is not the answer anymore
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| Jun 20, 2017 at 18:46 | comment | added | Majid | @RobertBryant Is that ok now? | |
| Jun 20, 2017 at 18:43 | comment | added | Majid | @RobertBryant Now I understood what you mean. Let me see how to correct the question. | |
| Jun 20, 2017 at 18:36 | comment | added | Robert Bryant | @Majid: Yes, to avoid confusion; by your definition, $\Sigma_2$ is not a sphere, even if $\Sigma_1$ is. | |
| Jun 20, 2017 at 18:29 | comment | added | Majid | @Robert Bayant unfortunately I did not get what your comment says. You mean I should use the word "unitary ball"? | |
| Jun 20, 2017 at 18:23 | comment | added | Robert Bryant | @Majid: The confusion is caused by the use of the word 'indicatrix', which you described as 'the unitary sphere' instead of as the 'unitary ball'. The unitary sphere (which is the usual meaning of 'indicatrix') is not convex, while the 'unitary ball' (whose boundary is the 'unitary sphere') is. | |
| Jun 20, 2017 at 18:22 | comment | added | Ben McKay | You said you wanted $\Sigma_1$ to be the unit sphere. But if $\Sigma_2$ contains both 1 and 2, it is not the boundary of a convex body containing the origin, i.e. not the unit sphere of any Minkowski norm. | |
| Jun 20, 2017 at 18:11 | comment | added | Majid | What is the problem by containing both 1 and 2? | |
| Jun 20, 2017 at 16:22 | comment | added | Ben McKay | If $\pi$ is not an isomorphism, then $\Sigma_2$ contains zero. | |
| Jun 20, 2017 at 16:20 | history | answered | Ben McKay | CC BY-SA 3.0 |