473 reputation
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bio website imsc.res.in/~amri
location Chennai, India
age 39
visits member for 3 years, 2 months
seen 3 hours ago

Professional mathematician.


Apr
16
comment Construct matrix of ones and zeros based on sequences
yes, your comment to the question is not off the mark - indeed such a matrix need not always exist. On the other hand, the Gale-Ryser theorem gives a necessary and sufficient condition for its existence for general sequences.
Apr
16
comment Construct matrix of ones and zeros based on sequences
If they don't sum up to the same constant, then the answer is somewhat trivially no, because the sums of both sequences will be the total number of $1$'s in the matrix.
Apr
16
comment Construct matrix of ones and zeros based on sequences
Then I am missing something.
Apr
16
awarded  Organizer
Apr
16
revised Construct matrix of ones and zeros based on sequences
Added a couple of tags
Apr
16
suggested suggested edit on Construct matrix of ones and zeros based on sequences
Apr
16
answered Construct matrix of ones and zeros based on sequences
Mar
15
comment If $AB=BA$ then they are diagonal
This is clearly false, take $A$ arbitrary and $B=A$. There is however, a statement that if $A$ and $B$ are diagonalizable and $AB=BA$ then $A$ and $B$ are simultaneously diagonalizable.
Feb
20
comment Suppose H and K are subgroups of a group G. If |H| = 12 and |K| = 35, what is |H intersection K|?
What can the cardinality of $H\cap K$ be?
Feb
18
awarded  Critic
Feb
17
comment Why is $\text{Hom}(V,W)$ the same thing as $V^* \otimes W$?
Have you thought about why it is $V^*\otimes W$ and not $V\otimes W$?
Feb
14
comment Calculating centre of rotation given point coordinates at different positions
It's called "Problems and Solutions" in the Mathematics Newsletter of the Ramanujan Mathematical Society. If you send me e-mail address (mine can be found at imsc.res.in/~amri, I can get in touch with you).
Feb
14
comment Calculating centre of rotation given point coordinates at different positions
It's a nice problem. Can I use it in a magazine column that I edit? How can I acknowledge you?
Feb
13
comment Calculating centre of rotation given point coordinates at different positions
You should be able to write out the equations of these lines. For example, slope of $L_1$ is the negative reciprocal of the slope of $P_1P_2$ and it passes through the midpoint $(\frac{x_1+x_2}2,\frac{y_1+y_2}2)$. Once you have these equations $y = m_1x+c_1$ and $y=m_2x+c_2$, find the intersection point by solveing $m_1x +c_1=m_2x+c_2$.
Feb
13
answered Calculating centre of rotation given point coordinates at different positions
Jan
16
comment Question regarding assumptions in Morera's theorem and conditions for existence of antiderivative.
Oh sorry, you are right. I was not reading this carefully. Of course, that $\Omega$ is simply connected is needed in the proof only to establish that the integral of $f$ does not depend on the path. If we already know that, we do not need this assumption. In fact, such an $f$ can be extended to a simply connected domain containing $\Omega$.
Jan
9
answered On a particular matrix homomorphism
Dec
31
answered Nice application of the Cauchy?-Frobenius?-Burnside?-Pólya? formula
Dec
19
awarded  Yearling
Dec
7
awarded  Commentator