Timeline for Why are inverse images more important than images in mathematics?
Current License: CC BY-SA 2.5
4 events
| when toggle format | what | by | license | comment | |
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| Dec 31, 2014 at 13:22 | history | made wiki | Post Made Community Wiki by Todd Trimble | ||
| Apr 27, 2010 at 17:49 | comment | added | Owen Biesel | If that's the question, the answer is no. Let $G$ be a cyclic group of prime order - then the requirement that a function $G\rightarrow G$ pull back subgroups to subgroups is very weak (it implies only that no nonzero element maps to zero), and most such functions won't be group homomorphisms. | |
| Apr 27, 2010 at 11:41 | comment | added | Qfwfq | As for the 2, I think he's actually asking whether a map of sets, such that the inverse image of every subgroup is a subgroup, is actually a group homomorphism. | |
| Apr 27, 2010 at 1:19 | history | answered | Sammy Black | CC BY-SA 2.5 |