Timeline for Category of groups = Category of models of group theory?
Current License: CC BY-SA 2.5
14 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 22, 2010 at 20:05 | answer | added | David E Speyer | timeline score: 1 | |
| Jan 22, 2010 at 18:31 | answer | added | Pete L. Clark | timeline score: 3 | |
| Jan 22, 2010 at 18:13 | answer | added | Theo Johnson-Freyd | timeline score: 2 | |
| Jan 22, 2010 at 14:59 | comment | added | Hans-Peter Stricker | That's right... | |
| Jan 22, 2010 at 14:54 | comment | added | David E Speyer | Just to check, by an elementary map of models you mean the definition here ncatlab.org/nlab/show/elementary+embedding , right? | |
| Jan 22, 2010 at 14:01 | vote | accept | Hans-Peter Stricker | ||
| Jan 22, 2010 at 13:51 | comment | added | Qiaochu Yuan | I don't follow. The word "same" has meaning only in context, and in the context of category theory, "same" means isomorphic. (Or equivalent.) If you aren't working within the context of category theory, then you should say so (and maybe not use the word "category" either). | |
| Jan 22, 2010 at 13:44 | answer | added | Joel David Hamkins | timeline score: 3 | |
| Jan 22, 2010 at 13:38 | vote | accept | Hans-Peter Stricker | ||
| Jan 22, 2010 at 14:01 | |||||
| Jan 22, 2010 at 13:25 | comment | added | Hans-Peter Stricker | Can two isomorphic abstract structures (only objects and arrows) be not the same? To talk at large: Isn't isomorphism a relation between two structures with at least one of them "concrete"? (This sums up in the question "What is 'abstract', what is 'concrete'?") | |
| Jan 22, 2010 at 13:18 | comment | added | Qiaochu Yuan | That is not a meaningful statement until you specify what you mean by "the same." Do you want a stricter or a looser notion than isomorphism? (For example, in practice most category theorists are happy with equivalence.) | |
| Jan 22, 2010 at 13:16 | comment | added | Hans-Peter Stricker | That's the point: are two isomorphic (abstract) categories the same? | |
| Jan 22, 2010 at 13:09 | comment | added | Qiaochu Yuan | You should probably specify what you mean by "the same." | |
| Jan 22, 2010 at 13:00 | history | asked | Hans-Peter Stricker | CC BY-SA 2.5 |