bio | website | |
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visits | member for | 5 years, 6 months |
seen | yesterday | |
stats | profile views | 783 |
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 |
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“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. |
Mar 25 |
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Jacobian of an injective mapping
@user126154: I meant the function $\phi: \mathbb{R} \to \mathbb{R}$ defined by $\phi(t) := J_f(a + t(b-a))$. |
Mar 25 |
comment |
Jacobian of an injective mapping
For the 2nd question apply the intermediate value theorem to $J_f$-restricted to the line joining a and b. |
Mar 12 |
accepted | Why the name “variety” and the notation “V” for zeroes of polynomials? |
Mar 11 |
awarded | Nice Question |
Mar 11 |
asked | Why the name “variety” and the notation “V” for zeroes of polynomials? |
Mar 10 |
comment |
Normal polytopes - counterexample?
Regarding the 'related question': M = dim(P) -1 suffices (Theorem 2.2.12, Toric Varieties, Cox-Little-Schenck). |