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19h
comment Determining North-South Line Via Non-digital Watch Method: Discussion on Background Theory
Hi: there are several reasons your post won't be well received. 1) the question isn't self contained (you make people hunt through unnumbered slides to read) 2) it's not really a mathematical question: it is a physics or astronomy question 3) you're asking too many questions. 4) you labeled it as a discussion (although it isn't really and you could easily remedy that )
23h
comment Show that $k[x,y]/(xy-1)$ is not isomorphic to a polynomial ring in one variable.
+1 That's a nice way to reduce the problem!
23h
comment Show that $k[x,y]/(xy-1)$ is not isomorphic to a polynomial ring in one variable.
@Learner Sorry if I misunderstood the hypotheses you intended. Hope you get an answer you like.
23h
comment Show that $k[x,y]/(xy-1)$ is not isomorphic to a polynomial ring in one variable.
@JyrkiLahtonen That's OK by me. These things can go either way sometimes.
1d
comment What do we call the ring homomorphism $R \rightarrow \mathrm{End}_{\mathbf{Ab}}(X)$ associated with an $R$-module $X$?
I was just thinking that representors of right modules would be fundamentally different since they map $R$ via a ring anti-homomorphism, so I wasn't sure you'd call them the same thing.
1d
comment Injective hull of a simple module
@karparvar Can you show such an $M$ has an essential socle? If so, the socle is simple by indecomposability, and then $M$ is the hull of that simple submodule.
1d
comment What do we call the ring homomorphism $R \rightarrow \mathrm{End}_{\mathbf{Ab}}(X)$ associated with an $R$-module $X$?
That is, the sidedness of the module.
1d
comment What do we call the ring homomorphism $R \rightarrow \mathrm{End}_{\mathbf{Ab}}(X)$ associated with an $R$-module $X$?
Thanks for letting me know. I had a feeling that's what you were talking about, but I feel it's best to ask if the notation isn't familiar. I've seen the image of this map, and its other-handed counterpart, discussed as sets, but I don't know I've seen a particular name for the function. The place most memorable about these for me is in Jacobson's Basic Algebra books. "Representor" is a pretty good working name, but it probably needs a side associated (?)
1d
comment What do we call the ring homomorphism $R \rightarrow \mathrm{End}_{\mathbf{Ab}}(X)$ associated with an $R$-module $X$?
What does the $\mathop{\lambda}_{x:X}$ mean?
1d
comment Rings leading to AKS primality test
For those (like me) not familiar with the abbreviation in the title: en.m.wikipedia.org/wiki/AKS_primality_test very interesting.
1d
comment Question on prime ideals of ${\mathbb Z}[x]$
If the downvoter has any legitimate concern about the answer, I would like to know what it is. Regards
2d
revised Show that quotient rings are not isomorphic
added 228 characters in body
Aug
28
comment Do approximate identities remain approximate identities if one adjoins 1 to a C* Algebra?
That is very weird. Maybe someday I will study this :) You really ought to write what you've discovered as an answer to your own question. I don't think it's totally trivial (it isn't trivial to me, anyhow.)
Aug
28
comment Do approximate identities remain approximate identities if one adjoins 1 to a C* Algebra?
Related, but probably not a dupe: math.stackexchange.com/q/432755/29335
Aug
28
comment Do approximate identities remain approximate identities if one adjoins 1 to a C* Algebra?
Scanning over approximate identities, I see I don't have a good enough feel for them to come to an immediate conclusion. But my feeling is that if you know how 1 is adjoined, you should be able to check directly.
Aug
28
comment Do approximate identities remain approximate identities if one adjoins 1 to a C* Algebra?
What method exactly are you using to adjoin the identity?
Aug
28
comment Let $V=\mathbb{R}^\mathbb{R}$, let $W$ be the subset of $V$ consisting of all monotonically inc or dec functions. Is $W$ subspace of $V$?
Obviously scalar multiplication doesn't cause a function to become nonmonotonic. The addition operation is the only remaining possible way it could fail, then. Seeing that, then experimentation should have quickly brought you to the examples below. That's a snapshot of how the problem could be solved.
Aug
28
comment If $M$and $N$ are R- modules, then under what conditions $\operatorname{Hom}(M,N)$ the space of R-module morphisms from M to N, is projective?
Add your thoughts to the post, not the comments. A lot of people are going to take one look at the body of your post, potentially downvote, and leave.
Aug
28
comment If $M$and $N$ are R- modules, then under what conditions $\operatorname{Hom}(M,N)$ the space of R-module morphisms from M to N, is projective?
Hi: Welcome to math.SE. Questions that treat the site as a "homework mill for question statements" are not well received. Generally, adding any substantive work and thoughts (even if they are not successful attempts) on a question will make it an admissible question. So, what have you tried up to now?
Aug
27
comment Non-artinian center
+1 Fascinating result!