• Today, 01:54
Yes, I don't see how the answers given by your book could possibly be correct.
3 replies | 15 view(s)
• Today, 01:52
Because we both made the same mistake reading the problem. We are told: Ahmad has x marbles. He has 40 more marbles than Weiming This means...
4 replies | 16 view(s)
• Today, 01:45
Looks good! (Yes)
1 replies | 13 view(s)
• Today, 01:38
Yes, that's good. Here, they are telling you: m+4=40 So, you need to solve for $$m$$ to determine how many pupils were there in the...
3 replies | 15 view(s)
• Today, 01:35
That looks good! (Yes)
4 replies | 16 view(s)
• Yesterday, 21:51
Thanks Steenis ... I appreciate your help ... Peter
2 replies | 47 view(s)
• Yesterday, 02:54
I am reading Paul E. Bland's book, "Rings and Their Modules". I am focused on Section 4.3: Modules Over Principal Ideal Domains ... and I need...
2 replies | 47 view(s)
• Yesterday, 01:53
Thanks for the help GJA ... But ... just a clarification ... I can verify that d \mid 1 and that d|1\Longrightarrow c|1 ... but I cannot follow...
3 replies | 108 view(s)
• August 14th, 2018, 22:26
Thanks GJA ... Appreciate your help ... Peter
4 replies | 96 view(s)
• August 14th, 2018, 12:36
Hello all, A friend of mine on another forum, knowing I am involved in the math help community, approached me regarding a question in statistics....
9 replies | 178 view(s)
• August 14th, 2018, 04:51
So because of the fact that $g$ is well-defined for any $x$ and $t$, and $u$ contains $g$, we get that the solution $u$ is unique? (Thinking) ...
5 replies | 134 view(s)
• August 14th, 2018, 01:07
Thanks GJA ... OK ... then consider the ring R = \mathbb{Z}_{6} \equiv \mathbb{Z} / 6 \mathbb{Z} = \{ \overline{0}, \overline{1}, \overline{2},...
4 replies | 96 view(s)
• August 14th, 2018, 00:11
Thanks to Steenis and Opalg for clarifying Bland Proposition 4.3.5 ... Hmm... ... seems that Bland made a bit of a mess of that Proposition ... ...
16 replies | 272 view(s)
• August 14th, 2018, 00:06
I am reading Paul E. Bland's book, "Rings and Their Modules". I am focused on Section 4.3: Modules Over Principal Ideal Domains ... and I need...
3 replies | 108 view(s)
• August 13th, 2018, 19:20
I would look at all factors present, and take the smaller power present in each: 2\cdot3^2\cdot7=126
3 replies | 86 view(s)
• August 13th, 2018, 11:34
The problem states:
5 replies | 119 view(s)
• August 13th, 2018, 00:43
Looks good! (Yes)
5 replies | 119 view(s)
• August 13th, 2018, 00:35
I just wanted to say, I'm really liking the way you title your threads usefully and show your work. (Yes)
3 replies | 61 view(s)
• August 13th, 2018, 00:14
You've got Kat and Nora right, but Devi would receive 24 + 2x (that's 2x more than Kate). And so the sum $$S$$ would be: ...
3 replies | 61 view(s)
• August 12th, 2018, 23:19
I am reading Dummit and Foote's book: "Abstract Algebra" (Third Edition) ... I am currently studying Chapter 10: Introduction to Module Theory ......
1 replies | 65 view(s)
• August 12th, 2018, 23:13
I am reading Dummit and Foote's book: "Abstract Algebra" (Third Edition) ... I am currently studying Chapter 10: Introduction to Module Theory ......
4 replies | 96 view(s)
• August 12th, 2018, 21:20
Thanks for the help Olinguito ... Your assistance is very much appreciated ... Peter
16 replies | 272 view(s)
• August 12th, 2018, 07:08
How could we show the uniqueness of the solution? Do we suppose that there is an other solution? (Thinking) Isn't it implied directly that $u$...
5 replies | 134 view(s)
• August 12th, 2018, 06:57
Hi Olinguito ... thanks again for your posts and help ... Now ... just a clarification ... In the post above, you write the following ... ...
16 replies | 272 view(s)
• August 12th, 2018, 05:17
Hello!!! (Wave) We have the Cauchy problem of the equation $u_t+xu_x=xu, x \in \mathbb{R}, 0<t<\infty$ with some given smooth ($C^1$)...
5 replies | 134 view(s)
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### 73 Visitor Messages

1. Welcome to the team of math helpers
2. Haha, that would be Mark. I like the way sounds, don't you?
3. Hey Balarka,

As far as I'm concerned, you are welcome to post such information in any thread no matter how old it is.
4. Hey, way to go!
5. Hey Balarka, thanks, glad you are enjoying the challenge! As for the origin of this particular problem, I'm not sure, I found it in https://www.math.muni.cz/~bulik/vyuka/pen-20070711.pdf (page 67, no solutions) and thought it was interesting. It only says "Japan 1990" so I'm guessing it's from a contest of some sort, yes (the second part of the challenge is a custom addition of mine).

Your proof appears to be correct although I will need some time to look at it in more detail. My solution approaches the problem in a similar way as yours, but proceeds somewhat differently, though I have not fully checked mine either (I will post it in a week as per the forum rules, as well as a reference solution if I can find one)
6. Done. Let me know if you need to edit more things in the future.
7. Hey Balarka,

topsquark was purposely given a wrong number and he wanted me to spot for the error, which it turns out, I was wrong. I guess I just am not good at math. Hehehe...
8. You should be able to edit it now. Let me know if there is a problem.
9. Hm, I'm interested in sending you a private message. Can you open up one space ?
10. I haven't had time to play with it, but it *is* interesting. The failure of right-exactness is what interests me: I suspect this is akin to why in groups left-split implies right-split, but not vice versa. So I would be tempted to investigate what a sufficient condition on $G$ would be so that the map: $Aut_N(G) \to Aut_N(H)$ is onto.

I feel the center of $G$ will be relevant, here, so I would look at the two extremes: $G$ abelian, and $G$ with trivial center. I think outer automorphisms will be troublesome. On the other hand if $H$ is an extension of $N$, and $G$ is an extension of $H$, this might be fruitful (again, mimicking the field construction).

For "concrete categories", for an object $A$ we can always form the group $Aut(A)$ of all isomorphisms $A \to A$. I can't say right off-hand if we can do so for ANY category, but this might be true (if our category is a poset, the automorphism groups are all trivial). So "some" generalization is possible, I'm not sure "how wide".
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#### Basic Information

Date of Birth
January 12, 2000 (18)
Biography:
I know a thing or two about topology. Find number theory interesting but don't know much about it.
Location:
West Bengal, India
Interests:
Number Theory
Country Flag:
India

#### Signature

Some of my notes on number theoretic topics are on a few primality tests and on Hardy & Littlewood's result (incomplete). The other articles are on quintics : about a brief description of Kiepert algorithm and a short introduction on quintic-solving algorithms, respectively. I have also written up an introductory thread on Riemann Hypothesis

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MarkFL
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