• Today, 18:19
Eileen has one leg shorter than the other. Is it ok to park where a sign says "Fine for parking"?
59 replies | 9708 view(s)
• Today, 05:54
MarkFL replied to a thread Evolution Self-Destructs in Chat Room
Haha...you went straight for the big gun..."Darwin's Bulldog" himself.
10 replies | 125 view(s)
• Today, 04:27
I just thought I would share with MHB members Duistermaat and Kolk "Remark on notation". This remark occurs after the definition of directional and...
2 replies | 31 view(s)
• Today, 00:56
If we integrate, we get: \ln|f(x)|=C-x This implies: f(x)=\pm e^{C-x}=\pm e^Ce^{-x} Now, let c_1=\pm e^{C} and also let $c_1=0$...
7 replies | 92 view(s)
• Today, 00:34
You haven't studied integration yet?
7 replies | 92 view(s)
• Today, 00:15
Let's use the notation of Leibniz and write: \d{f}{x}=-f(x) Now what if we separate variables and write: \frac{1}{f(x)}\,df=-dx We have...
7 replies | 92 view(s)
• Yesterday, 23:41
Hello, and welcome to MHB! (Wave) Do you mean: f(x)=-f'(x) ?
7 replies | 92 view(s)
• Yesterday, 23:30
I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2:...
2 replies | 31 view(s)
• Yesterday, 23:01
I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2:...
0 replies | 25 view(s)
• Yesterday, 22:24
MarkFL replied to a thread Evolution Self-Destructs in Chat Room
According to what I could find online, Dr. Morris is a young Earth creationist with a degree in geological engineering. If you can point to the peer...
10 replies | 125 view(s)
• Yesterday, 22:14
MarkFL replied to a thread Evolution Self-Destructs in Chat Room
This argument sounds very similar to: Watchmaker analogy The above article contains some noteworthy criticisms of the analogy. :)
10 replies | 125 view(s)
• Yesterday, 15:25
It's a "rite of passage" for calculus students. (Smile)
3 replies | 55 view(s)
• Yesterday, 07:20
l will now attempt to, explicitly, complete the demonstration that Df(a) v = \sum_{ 1 \le j \le n } v_j D_j f(a) \ \ \ \ (v \in \mathbb{R}^n ) ...
4 replies | 76 view(s)
• Yesterday, 01:11
Here is an attempt to show Df(a) v = \sum_{ 1 \le j \le n } v_j D_j f(a) \ \ \ \ (v \in \mathbb{R}^n ) Now we have ... Df(a) v =...
4 replies | 76 view(s)
• Yesterday, 00:59
Thanks Country Boy ... ... appreciate the help ... Peter
4 replies | 76 view(s)
• Yesterday, 00:54
Thanks GJA ... that was really helpful ... Still reflecting on what you have said ... Thanks again ... Peter
2 replies | 63 view(s)
• February 21st, 2018, 23:26
Here is this week's POTW: Let $ABCD$ be a convex quadrilateral with $\overline{AB}=\overline{AD}$. Let $T$ be a point on the diagonal...
0 replies | 45 view(s)
• February 21st, 2018, 23:21
No one answered this weeks POTW...my solution follows: (a) Apply conservation of angular momentum (subscripts of $R$ pertain to the rod, while...
2 replies | 160 view(s)
• February 21st, 2018, 07:38
I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2:...
4 replies | 76 view(s)
• February 21st, 2018, 06:50
I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2:...
1 replies | 42 view(s)
• February 21st, 2018, 00:31
\frac{5}{4}\cdot\frac{4}{3}=\frac{5}{3} :)
14 replies | 228 view(s)
• February 20th, 2018, 23:10
MarkFL posted a visitor message on Peter's profile
Sometimes editing a thread title is an issue, but the issue is with vBulletin. If you ever want to change a thread title, and can't, just let me know...
• February 20th, 2018, 22:24
Thanks again Krylov .... BUT ... just a comment on D&K's proof .... I have to say that D&K's proof of Hadamard's Lemma though valid, is not...
3 replies | 82 view(s)
• February 20th, 2018, 21:57
I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2:...
0 replies | 27 view(s)
• February 20th, 2018, 21:26
I am reading "Multidimensional Real Analysis I: Differentiation" by J. J. Duistermaat and J. A. C. Kolk ... I am focused on Chapter 2:...
2 replies | 63 view(s)
• February 20th, 2018, 20:41
Thanks Krylov, ... followed your advice and obtained the result ... Thanks again ... Peter
3 replies | 82 view(s)
More Activity

72 Visitor Messages

1. Haha, that would be Mark. I like the way sounds, don't you?
2. Hey Balarka,

As far as I'm concerned, you are welcome to post such information in any thread no matter how old it is.
3. Hey, way to go!
4. 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)
5. Done. Let me know if you need to edit more things in the future.
6. 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...
7. You should be able to edit it now. Let me know if there is a problem.
8. Hm, I'm interested in sending you a private message. Can you open up one space ?
9. 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".
10. Yes, you are correct. The first post in a thread may be edited within 2 hours, and all other posts within 24 hours.

However, if you run over the 24 hour limit, I will lift the limit for you temporarily since you are adding such great content.
Showing Visitor Messages 11 to 20 of 72
Page 2 of 8 First 1234 ... Last
Page 2 of 8 First 1234 ... Last

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

Statistics

Total Posts
573
Posts Per Day
0.32
Thanks Given
699
1,378
2.405
Visitor Messages
Total Messages
72
Most Recent Message
December 24th, 2017 18:27
General Information
Last Activity
December 24th, 2017 18:32
Last Visit
December 24th, 2017 at 18:32
Last Post
January 1st, 2017 at 22:39
Join Date
March 22nd, 2013
Referrer
MarkFL
Referrals
2
Referred Members
neelmodi, zuby

17 Friends

1. agentmulderOffline

MHB Apprentice

MHB Master

3. BacteriusOffline

MHB Journeyman

MHB Master

5. FantiniOffline

MHB Craftsman

6. MarkFLOnline

Pessimist Singularitarian

7. mathmaniacOffline

MHB Craftsman

8. mente oscuraOffline

MHB Craftsman

MHB Master

10. PetrusOffline

MHB Journeyman

Showing Friends 1 to 10 of 17
Page 1 of 2 12 Last