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17h
answered Simple generator modules
2d
comment if the sum of two units is a unit, then there is an unique maximal ideal
@RobbeMotmans What good is insisting on what your book says when you have just been shown that this is false in rings other than $\{0\}$? The question with "units" replaced with "nonunits" appears many times already here on math.SE.
2d
comment Why do lines in the poincare model meet the infinite edge at right angles?
So you want an explanation that assumes the hyperbolic sheet model, and you want to see how that makes the right angles in the Poincare model?
Apr
23
revised $X$ is A-space iff the frontier of any closed set in $X$ is compact.
edited title
Apr
23
comment Is there a counterexample for the claim: if $A \oplus B\cong A\oplus C$ then $B\cong C$?
This question gets asked from time to time, but it looks like the duplicates are hard to track. This one also adds the question about finite generation, so maybe others will become duplicates of this.
Apr
23
answered What are all the integral domains that are not division rings?
Apr
22
comment Show that if $r$ is nilpotent in a ring with identity, then $1-r$ is a unit in $R$
This is the third question you've asked recently closed because it duplicates many previous questions. Please take advantage of the search feature before you ask a question.
Apr
22
answered Why is it called the category of representations?
Apr
22
answered Uniqueness of prime ideals of $\mathbb F_p[x]/(x^2)$
Apr
22
comment Nilpotent elements in group algebra
Interesting! I have not seen this reference before.
Apr
21
comment Nilpotent elements in group algebra
Are we sure this question has a positive answer? Where did it come from?
Apr
21
revised Problems with understanding the proof of noetherian ring
added 316 characters in body
Apr
21
comment Problems with understanding the proof of noetherian ring
@user136266 Incidentally, what user73985 says is just fine. Submodules of submodules are submodules.
Apr
21
comment Problems with understanding the proof of noetherian ring
@user136266 Certainly not. I think I may see the source of your confusion, and I expanded my answer a bit to explain. Let me know if it's helpful or not.
Apr
21
revised Problems with understanding the proof of noetherian ring
added 939 characters in body
Apr
21
answered Problems with understanding the proof of noetherian ring
Apr
21
revised Some theorems in euclidean geometry have incomplete proofs
Removing tags that don't fit
Apr
21
comment Is the zero ideal $\{0_{M_2(\mathbb{R})}\}$ maximal in $M_{2}(\mathbb{R})$?
@Jellyfish : $M_2(\Bbb R)$ is not a division ring.
Apr
20
comment Bourbaki Algebra Chapter IV - Exercise 9(b)
By forcing readers to go find this book, you are screening out most of the audience capable of helping you. Even if someone has that book and wants to help you, maybe they can't be bothered to look up the whole problem for you. You have it right there, just write it down...
Apr
20
revised Characteristic of a Finite Integral Domain
added 513 characters in body