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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.
Mar
25
comment 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).
Feb
19
comment What are some mathematical sculptures?
@ToddTrimble: Hi Todd, it had a "coppery" look, but not sure if it was mixed with anything else.
Feb
4
accepted How many of the true sentences are provable?