9,568 reputation
1923
bio website math.tulane.edu/~mjoyce3
location New Orleans, LA, USA
age 36
visits member for 2 years, 11 months
seen 9 hours ago

I am interested in algebraic combinatorics related to Schubert calculus and the geometry of spherical varieties.


Apr
14
comment Two path test in calculus
Hint for the specific limit problem given: Consider the approach of the origin along the curves $y = kx^2$ for different values of $k$.
Apr
14
answered Triple integral formula
Apr
14
revised Two continuous functions agree on an open subset of an irreducible space.
edited body
Apr
14
answered Two continuous functions agree on an open subset of an irreducible space.
Apr
14
comment Which of the following expresses the fact that the vectors $u$ and $v$ have the same length?
To help further your understanding, you might ask yourself which of the four equations expresses the fact that the vectors $u$ and $v$ have the same direction. (A correct answer is among the four listed choices.)
Apr
14
comment Which of the following expresses the fact that the vectors $u$ and $v$ have the same length?
What is your basis for thinking the answer is (b)? Why are you ruling out the first and last choices? It is much easier to help you when you explain your thought process.
Apr
14
comment (12345) is an even permutation of S_5. True or False?
That's right. An permutation is even if and only if it can be expressed as a product of an even number of transpositions.
Apr
14
comment Limits of Indeterminate Powers in Exponential Form using L'Hopital's Rule
Technically, you're taking the limit as $x \rightarrow 0^+$ since $x^x$ is only defined for $x > 0$.
Apr
14
revised Limits of Indeterminate Powers in Exponential Form using L'Hopital's Rule
Fixed LaTeX formatting
Apr
14
revised We are interested in price of a commodity, traded at regular intervals. Why it is reasonable to take $a$, $c$, and $d > 0$ and $b < 0$?
Fixed LaTeX
Apr
14
revised Distance of a point to a plane
Fixed LaTeX; gave more succient title
Apr
14
revised Proving That a $1 \times 1$ Matrix has a Rank of $1$
Fixed LaTeX
Apr
13
answered Changing of limits of integral
Apr
13
revised Placing two queens on an $n \times m$ chessboard
edited tags; edited title
Apr
13
revised Is $W$ a subspace of $\mathbb{R}^{n \times n}$?
Fixed LaTeX in title
Apr
13
revised Checking the maximality of an ideal
Fixed LaTeX formatting
Apr
13
answered Is my proof correct? The group of rigid motions of the cube is $\cong S_4$.
Apr
13
comment Is my proof correct? The group of rigid motions of the cube is $\cong S_4$.
It is hard to follow your surjectivity argument without a diagram indicating labeling the vertices. If this is a homework assignment, I would suggest including one in your write up that you turn in. It sounds like your $s$ sends $4$ to $3$ (the first transformation sends $4$ to $1$ and the second transformation sends $1$ to $3$), so it does not appear to be what you want in order for $\phi(s) = (1, 2)$. There's an easier proof for surjectivity (see answer below).
Apr
12
comment Give an example of a function from $X$ to $Y$
That's correct!
Apr
12
comment Give an example of a function from $X$ to $Y$
As further practice, you might try to figure out how many functions $g : Y \rightarrow X$ there are.