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awarded  Popular Question 
Nov
23 
awarded  Nice Question 
Nov
19 
comment 
Standard polynomials applied to matrices (bis)
How do you get a map from $M_2(\mathbb{R})$ to itself via $S_2$? Do you fix one of the factors? 
Nov
17 
awarded  Popular Question 
Nov
5 
awarded  Yearling 
Oct
22 
awarded  Popular Question 
Oct
22 
answered  Can a curve intersect a given curve only at given points? 
Oct
21 
awarded  Enlightened 
Oct
21 
awarded  Nice Answer 
Jun
5 
revised 
When is $f(x^d)$ irreducible?
added 344 characters in body 
Jun
5 
revised 
When is $f(x^d)$ irreducible?
added 75 characters in body 
Jun
5 
answered  When is $f(x^d)$ irreducible? 
Jun
5 
accepted  The space of polynomials with all real roots 
Jun
5 
revised 
The space of polynomials with all real roots
added 255 characters in body 
Jun
4 
asked  The space of polynomials with all real roots 
Apr
27 
comment 
What is the fan of the toric blowup of $\mathbb{P}^3$ along the union of two intersecting lines?
Well, $w \equiv 0$ on both $C_i$, so definitely $wz$ is in the ideal, no? 
Apr
23 
comment 
induced map on tangent bundles from blow up morphism
Note that tangent bundle is dual to cotangent bundle. Since the cotangent space at a point $y \in Y$ is simply $m_y/m_y^2$, where $m_y$ is the ideal of $y$, given a morphism $\phi: Y \to Z$ such that $\phi(y) = z$, you get an induced map from the cotangent space at $z$ to the cotangent space at $y$. Now dualize. 
Feb
28 
comment 
Blowingup a point in the singular locus
Can you please add the definition of an ordinary singularity? 
Feb
24 
comment 
“Exceptional components” of the exceptional divisor of a blow up
@KarlSchwede: yes, $\overline{\lbrace P \rbrace} \neq V$, and you are right in all other counts. 
Feb
24 
asked  “Exceptional components” of the exceptional divisor of a blow up 