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Jun
18
comment If $H$ and $K$ are solvable subgroups of G with $H$ normal in $G$, then $HK$ is a solvable subgroup of $G$
If this problem is true, then your question is a false one. Replacing $G$ with $HK$, you'd get a counterexample to this question. Where did you find the problem?
Jun
18
comment What will the recursion tree of Fibonacci series look like?
@MaksimDmitriev Done.
Jun
18
revised What will the recursion tree of Fibonacci series look like?
added 657 characters in body
Jun
18
comment Modules over a monoid: trouble with the definition.
I was going to say that it is just a writing convention to simplify writing the action, but Zev has beaten me to it. There is no pre-existing operation.
Jun
18
comment Riemannian geometry vs Hyperbolic geometry
This reminds me of a question I once asked about hyperbolic geometry and spaces with indefinite metric signature which you may find useful.
Jun
15
answered Is the zero ring a domain?
Jun
15
comment Algebra. If $R$ is a commutative associative ring with neutral element.
@MattSamuel : I agree with Bill in this case. Prime ideals are explicitly defined to be proper ideals of $R$ in every text I know (which is a lot), no exceptions. Allowing the entire ring to be a prime ideal does not "fit" into the big scheme well. However, $R$ is allowed to be a semiprime ideal in the same texts.
Jun
14
answered Prime ideals in a Dedekind domain
Jun
12
comment Characteristic of nonzero commutative rings with unity
@JessePFrancis For the second comment: you are telling me that you can't think of a single ring $R$ with characteristic $p$ and then forming $R\times R$?
Jun
12
comment Characteristic of nonzero commutative rings with unity
@JessePFrancis For the first comment, you're just supposed to work with the fact that $n\cdot\phi(1)=\phi(n\cdot 1)$
Jun
12
answered Characteristic of nonzero commutative rings with unity
Jun
11
answered Commutative Monoid and Invertible Elements
Jun
11
comment Commutative Monoid and Invertible Elements
Does "lots" mean "infinitely many" here?
Jun
11
comment Commutative Monoid and Invertible Elements
Lots of commutative rings would furnish you with such a monoid...
Jun
10
comment affine vs projective tranformation
@Maystro This description you just gave isn't making a lot of sense to me. If you carefully explain the problem again, maybe I will see what you mean.
Jun
10
comment affine vs projective tranformation
You can puzzle out what the extra entries do explicitly, but I'm not sure it is worth the effort. It depends on your needs if the effort will gain you anything.
Jun
10
answered affine vs projective tranformation
Jun
9
comment Boolean algebra-Boolean ring. Stone Theorem?
This is pretty unreadable. Does A¯¯¯¯ mean $\overline{A}$? Does A⊓B mean $A\cap B$, as I suspect?
Jun
9
comment A commutative noetherian ring in which each ideal $I$ is principal and $I^2=I$ must be a finite product of fields
@henry Maybe you mean "each principal ideal is idempotent"?
Jun
9
comment Left ideals in a subring of $M_2(R)$
maybe. It is an interesting question :) It is not "far" from Morita theory. Have you ever heard of a "Morita context ring"?