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visits | member for | 4 years, 5 months |
seen | Apr 16 at 11:18 | |
stats | profile views | 727 |
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 |
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Normal polytopes - counterexample?
Regarding the 'related question': M = dim(P) -1 suffices (Theorem 2.2.12, Toric Varieties, Cox-Little-Schenck). |
Feb 19 |
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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? |
Feb 1 |
awarded | Enlightened |
Feb 1 |
awarded | Nice Answer |
Jan 31 |
comment |
Is the induced ring homomorphism surjective for a finite injective morphism between affine varieties?
Just wanted to add that in your first statement above, "affine" is not necessary. Essentially the same argument shows that "a finite bijective morphism f:X→Y between varieties where Y is normal must be an isomorphism." |
Jan 31 |
revised |
Is the induced ring homomorphism surjective for a finite injective morphism between affine varieties?
added 428 characters in body |
Jan 31 |
answered | Is the induced ring homomorphism surjective for a finite injective morphism between affine varieties? |
Nov 28 |
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Computing fundamental groups of the complement of plane curves
@Jason: I see I was being dense. Thanks again. |
Nov 28 |
revised |
Computing fundamental groups of the complement of plane curves
added 32 characters in body |
Nov 28 |
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Computing fundamental groups of the complement of plane curves
@Ian: Thanks - I will take a look. |
Nov 28 |
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Computing fundamental groups of the complement of plane curves
@Jason: I don't think I have written anything wrong. In any event, I edited the question to make it (hopefully) clearer. Thanks. |
Nov 28 |
revised |
Computing fundamental groups of the complement of plane curves
added 367 characters in body |
Nov 28 |
comment |
Computing fundamental groups of the complement of plane curves
@Jack: You are right. But I want to know how, for a fixed (not necessarily nice) $C$, to choose $D$ so that every loop in $\mathbb{P}^2-C$ can be deformed into a loop in $D-C$. Even in this case $D$ can be chosen to be a generic line. But can we take it to be a generic element in any other linear system (not necessarily containing lines)? |