10,318 reputation
11228
bio website math.tulane.edu/~mjoyce3
location New Orleans, LA, USA
age 36
visits member for 3 years, 3 months
seen 19 hours ago

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


Oct
21
answered Algebraic Proofs in Combinatotics
Oct
16
answered Solve $\sqrt{3x}+\sqrt{2x}=17$
Oct
15
comment Proving or disproving A+B is invertible
@anderstood: You're absolutely right. My nitpick was a (very, very minor) aesthetic one, not a critique of the actual content.
Oct
15
awarded  Yearling
Oct
14
comment Proving or disproving A+B is invertible
And now you have a second proof that $AB \neq BA$ for your specific example! ;) Small nitpick: if we're assuming $A$ is $k$-nilpotent, then the sum in your formula needs only to run from $i = 0$ to $i = k - 1$.
Oct
14
answered Proving or disproving A+B is invertible
Oct
14
answered A question about Klaus Hulek algebraic geometry
Oct
14
revised What is the ratio between the speed of the boat and speed of the water current?
edited tags
Oct
12
comment Is it true that $\langle a+cb, a+cb\rangle = \langle a,a\rangle + c^2 \langle b,b\rangle $ where $a,b \in \mathbb{R}^n$ and $c \in \mathbb{R}$?
It's not true in general. You need either $c = 0$ or $\langle a, b \rangle = 0$.
Oct
12
answered Game Theory - First move vs second move advantage?
Oct
11
answered Definition of equivariant map if one of the actions is a right action
Oct
6
comment Tom can choose from $4$ soups, $5$ salads and $4$ drinks for his lunch. How many different combinations of a soup, a salad, and a drink can he make?
Tom should go with French onion, Caesar, and water, and ignore any other combination. (But see Farzad's answer to see how many combinations he's excluding.)
Oct
6
answered how do we know that the rank of AB will be less than a number?
Oct
3
revised Proof that $\operatorname{ker}(A^{T}A) = \operatorname{ker}(A)$?
added 18 characters in body
Oct
3
answered Proof that $\operatorname{ker}(A^{T}A) = \operatorname{ker}(A)$?
Sep
30
awarded  Explainer
Sep
26
comment What is the difference between the algebraic function fields and the fields itself
$(F,K)$ is not a set. It is a pair of sets. So you cannot talk about an "element" of $(F,K)$.
Sep
25
comment Group and subgroup of $G$
I don't understand your sentence `The inverse of $H$ is not an integer.' $H$ is a subset, not an element. Moreover, the elements of $H$ themselves are not integers.
Sep
25
revised Group and subgroup of $G$
added LaTeX formatting
Sep
25
comment What is the difference between the algebraic function fields and the fields itself
It's not proper to write $z \in F / K$, because $F/K$ really refers to the field extension (as anon pointed out in the comments), not to the field $F$. Formally, you can think of a field extension as a pair $(F,K)$ of fields with $K \subseteq F$.