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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 blow-up 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 Blowing-up 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
Jan
20
accepted Is being reduced a generic property of schemes?
Jan
19
comment Is being reduced a generic property of schemes?
Dear Sándor, not sure I get the example: your $Y$ is nowhere reduced, so it does not satisfy the assumption of being generically reduced.
Jan
19
asked Is being reduced a generic property of schemes?
Nov
5
awarded  Yearling
Aug
25
comment A question on resolution of singularities
Is it true that $\pi$ restricts to an isomorphism on $Y\setminus \pi^{-1}(\{p\} \cup L)$, so that it does not change any point on $\mathbb{P}^4 \setminus (\{p\} \cup L)$? If this is true then the answer is clearly negative.
Jul
2
awarded  Curious
Jun
29
revised What is the probability that a random sequence of polynomials is regular?
deleted 5 characters in body
Jun
26
answered What is the probability that a random sequence of polynomials is regular?
Mar
25
comment Jacobian of an injective mapping
@user126154: you are right. I saw in the question $J_f(a) < 0$, and immediately interpreted $J_f$ as the Jacobian determinant.