Timeline for Why semigroups could be important?
Current License: CC BY-SA 2.5
26 events
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| Feb 3, 2020 at 18:04 | comment | added | Michael | Natural number form a semigroup, but not a group. Most rings are semigroups, but not groups relative to multiplication operation. Matrix determinant is a morphism from a multiplicative semigroup of matrices to the multiplicative semigroup of $\mathbb{R}$ or $\mathbb{C}$ (or whatever field your matrices were define over). Perhaps I don't understand the question, for it seems to me that semigroups are used all the time... | |
| Feb 3, 2020 at 16:18 | history | edited | Zach Teitler |
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| Feb 3, 2020 at 11:24 | history | edited | YCor |
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| Jan 2, 2014 at 22:43 | answer | added | eventually | timeline score: 4 | |
| Jan 2, 2014 at 22:39 | answer | added | TT_ stands with Russia | timeline score: 3 | |
| Nov 14, 2013 at 18:32 | comment | added | Michał Masny | A related question from MSE: math.stackexchange.com/questions/101487/… | |
| Feb 25, 2011 at 23:42 | answer | added | Yemon Choi | timeline score: 14 | |
| Feb 19, 2011 at 17:33 | answer | added | weakstar | timeline score: 2 | |
| Feb 19, 2011 at 10:35 | answer | added | Denis Serre | timeline score: 10 | |
| Feb 18, 2011 at 20:39 | answer | added | András Bátkai | timeline score: 4 | |
| Feb 18, 2011 at 19:58 | comment | added | Yemon Choi | @Victor: your comment to Martin B suggests that perhaps your underlying question is really the following: is the general theory of semigroups as important in wider mathematics as the general theory of groups is? If that is roughly what you were driving at, then perhaps the answer is a guarded "no", because there is so little one can say about an arbitrary semigroup. For particular classes of semigroup, though, there does seem to be fruitful general theory | |
| Feb 18, 2011 at 19:54 | comment | added | Yemon Choi | When you say C_0-semigroups aren't really semigroups, perhaps you could explain what really is a semigroup? | |
| Feb 18, 2011 at 19:51 | answer | added | BSteinhurst | timeline score: 7 | |
| Feb 18, 2011 at 19:50 | comment | added | Yemon Choi | Important to whom, and for what? (Less facetiously; not everything in life is reversible.) | |
| Feb 18, 2011 at 19:42 | answer | added | user6976 | timeline score: 8 | |
| Feb 18, 2011 at 19:40 | answer | added | Apollo | timeline score: 5 | |
| Feb 18, 2011 at 19:34 | comment | added | Steve Huntsman | The renormalization "group" is really a semigroup. | |
| Feb 18, 2011 at 19:03 | answer | added | Michal Kotowski | timeline score: 9 | |
| Feb 18, 2011 at 18:55 | comment | added | Mariano Suárez-Álvarez | Shouldn't this be titled "Why are semigroups important?" :) | |
| Feb 18, 2011 at 18:49 | answer | added | mhum | timeline score: 13 | |
| Feb 18, 2011 at 18:41 | comment | added | Victor | @Martin: ok, in PDE's, in computer science (say, particularly, semi-Thue systems), the so-called Cuntz-algebras in C*-algebras etc. -- all this is where semigroups appear is like there appears something with associative operation and that's it, no further miracle of that we then go looking what is going on with those semigroups with further yielding nice results about our initial problem. And, C_0-semigroups aren't really semigroups :-) I'm not saying that semigroups are not important, I just wonder if somebody knows where semigroups can do some tricks (hence it's a good research question) | |
| Feb 18, 2011 at 18:30 | comment | added | Martin Brandenburg | @Victor: The wikipedia article shows that semigroups are important in applied mathematics, PDE, theoretial computer science and probability theory ... perhaps you should explain why you think that this is not evidence enough for their importance. Check also related articles such as en.wikipedia.org/wiki/C0-semigroup | |
| Feb 18, 2011 at 18:24 | comment | added | Martin Brandenburg | @Jim: Yes, perhaps this question asks for a direction where to begin ... | |
| Feb 18, 2011 at 18:21 | comment | added | Jim Humphreys | This is an extremely general question, given that whole books have been written about semigroups or monoids. | |
| Feb 18, 2011 at 18:18 | answer | added | Gerhard Paseman | timeline score: 2 | |
| Feb 18, 2011 at 18:09 | history | asked | Victor | CC BY-SA 2.5 |