All Questions
Tagged with ag.algebraic-geometry motives
359 questions
4
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1
answer
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Grothendieck's letter to Serre on the Standard Conjectures
Is it the letter dated in 27/08/1965 of Grothendieck where he presents to Serre the Standard conjectures on algebraic cycles?
- 61
8
votes
1
answer
380
views
Is the Tate conjecture known for etale covers of products of curves
Let $X$ be a (smooth projective geometrically connected) surface over a finitely generated field $k$. The Tate conjecture predicts that, for $l$ a prime number invertible in $k$, the Chern class map ...
- 83
4
votes
0
answers
306
views
What is the relation between Beilinson's conjectures and Standard conjectures of algebraic cycles?
Do Standard conjectures on the K-theory of varieties over finite field have implications in the motivic cohomology of Z where exist the correct formalism of Beilinson's conjectures?
What is the ...
user55909
42
votes
1
answer
6k
views
Progress on the standard conjectures on algebraic cycles
What's the current state of these conjectures?
Who is working on them?
In "Standard conjectures on algebraic cycles" Grothendieck says:
"They would form the basis of the so-called "theory of ...
user55909
0
votes
1
answer
388
views
Articles about Weil cohomology theory by Grothendieck and Artin
In "The Standard Conjectures" Kleiman says that the following properties of Weil cohomology theory were proved in 1963 for étale cohomology by Artin and Grothendieck, except for the last one that it ...
user55909
8
votes
1
answer
467
views
Known norm varieties and the Bloch-Kato conjecture
The Bloch-Kato conjecture states that
$K_M^n(k)/l \simeq H^n(k,\mu^{\otimes n}_l)$ for every $n,l$,while $l$ is invertible in $k$.
A important part in the proof of the Bloch-Kato conjecture is to ...
- 1,479
29
votes
3
answers
2k
views
$\zeta(n)$ as a mixed Tate motive
I am trying to understand why there exists, for each $n \geq 2$, a mixed Tate motive $M$ over $\mathbb{Q}$ such that
$M \in Ext^1_{MT(\mathbb{Q})}(\mathbb{Q}(0), \mathbb{Q}(n))$
and $\zeta(n)$, ...
- 291
4
votes
1
answer
628
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why Borel's computation implies Beilinson-Soulé?
Let $k$ be a field of characteristic zero and $DM(k)_{\mathrm{Q}}$ Voevodsky's category of motives over $k$ with rational coefficients. The Beilinson-Soulé conjecture says
$$
\mathrm{Hom}_{DM(k)_{\...
- 41
20
votes
1
answer
902
views
Is there any publication of Bombieri about the standard conjectures on algebraic cycles?
In "Standard conjectures of algebraic cycles" Grothendieck says:
"... These [Standard conjectures] are not really new, and they were worked out about three years ago independently by Bombieri and ...
user51486
13
votes
1
answer
591
views
Is there a yoga of effectivity for motives and their realizations?
Inside the 'usual' categories of motives (Chow, Voevodsky ones) there are the categories of effective motives. Similarly, there are effective Hodge structures; they seem to be closely related with ...
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10
votes
2
answers
1k
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What implications would a solution of the *Standard Conjectures* have on the *Hodge Conjecture*?
I'm new to the field, so I just would like to know what implications would have a solution of the Standard Conjectures on the Hodge Conjecture. I read somewhere they are related in some way, but I don'...
- 101
0
votes
1
answer
149
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Rost Correspondence and minimal Pfister-Neighbors
In http://www.math.uiuc.edu/K-theory/0357/ Karpenko utters the following:
Conjecture 1.6. If an anisotropic quadric $X = Q$ possesses a Rost correspondence,
then the quadratic form (defining $X$) ...
- 1,479
8
votes
0
answers
184
views
Can the failure of the multiplicativity of archimedean L-factors be corrected?
My question is parallel to J. Borger' question:
Can the failure of the multiplicativity of Euler factors at bad primes be corrected?
As emphasized by Scholbach in his paper on special values of L-...
4
votes
1
answer
339
views
tensor of motives
Let $X$ and $Y$ be two smooth projective varieties over $k$. Consider the Chow motives $M(X\times\mathbb{P}^n)\simeq M(X)\otimes M(\mathbb{P}^n)$ and $M(Y\times\mathbb{P}^n)\simeq M(Y)\otimes M(\...
- 741
19
votes
3
answers
2k
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$p$-adic periods
For a variety $X$ defined over $\mathbb{Q}$, there's a (functorial) comparison isomorphism
$$
H^i_{dR}(X)\otimes\mathbb{C}\to H^i_B(X,\mathbb{Q})\otimes\mathbb{C}.
$$
If we pick $\mathbb{Q}$-bases for ...
- 9,061
10
votes
1
answer
398
views
Cohomology of relative motives
Notation
Let $S$ be a scheme, proper over a field $k$. Let $\mathrm{SmPr}_{S}$ denote the category of smooth projective $S$-schemes. Let $\mathcal{M}_{S}$ denote the category of relative Chow motives ...
- 5,504
18
votes
4
answers
2k
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Applications of homotopy purity theorem of Morel-Voevodsky
One of the most important theorems in motivic homotopy theory is the homotopy purity theorem of Morel-Voevodsky which says that the motivic Thom space of the normal bundle $\mathcal N_{Z/X}$ of a ...
- 805
5
votes
0
answers
801
views
Two questions on motivic homotopy theory
I am a beginner in motivic homotopy theory and motivic cohomology and have just begun reading books by Dundas et al. and Mazza-Voevodsky-Weibel. I have two basic questions:
Why is the question of $\...
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30
votes
1
answer
4k
views
Reasons for the use of Nisnevich topology in motivic homotopy theory
The objects of interest in motivic homotopy theory are "spaces"-which are simplicial sheaves of sets on the big Nisnevich site $Sm/k$ of smooth schemes of finite type over a field $k$. I understand ...
- 805
1
vote
1
answer
417
views
Rost-Motive for n > 2
Have a look on the paper
F. Morel, Voevodsky's proof of Milnor's conjecture, Bull. Amer. Math. Soc. 35 (1998), 123-143, doi:10.1090/S0273-0979-98-00745-9.
and go to example 6.5 please.
In this ...
- 193
1
vote
0
answers
140
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The right (not the left 'Suslin complex' one) adjoint to the embedding of $ DM^{eff} $ into $D(ShvTr) $?
Inside the derived category of Nisnevich sheaves with transfers there is the category $DM^{eff} $ of Voevodsky's effective motivic complexes (actually, Voevodsky only considered bounded above ...
- 16.9k
4
votes
0
answers
205
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Finer motivic decomposition in a bigger motivic category
In his Ph.D. thesis, Semenov shows that the motivic decomposition of a variety in general is not unique. He works in the category of Chow-Motives and not in a bigger category of motives.
Is there an ...
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31
votes
1
answer
4k
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For which varieties is the natural map from the Chow ring to integral cohomology an isomorphism?
My apologies if this question is too naive.
Let $X$ be a smooth projective complex variety. There is a natural map $A^{\bullet}(X) \to H^{2\bullet}(X)$ of graded rings from the Chow ring of $X$ to ...
- 118k
6
votes
0
answers
230
views
Nice references for injective model structures and Quillen functors between motivic homotopy categories
It seems that for the injective model structures for the categories simplicial presheaves and simplicial Nisnevich sheaves (on the category of smooth varieties over a perfect field $k$) there exist ...
- 16.9k
13
votes
0
answers
892
views
Stack of Tannakian categories? Galois descent?
I'm having trouble finding a reference for something that I'm guessing the experts worked out long ago. Let's take a local or global field $F$ for this post, and fix a separable algebraic closure $\...
- 13.3k
15
votes
1
answer
2k
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Moduli space of motives vs moduli space of varieties
A (projective) abelian variety $A$ over the complex numbers is determined by $H^1(A,\mathbb{Z})$ together with its Hodge structure and polarization. This miracle means that one can parametrise ...
- 829
4
votes
1
answer
451
views
$T$-stable vs. $S^1$-stable motivic homotopy category: which sorts of transfers are available?
I would like to have some sort of transfers in motivic stable homotopy categories in order to adapt Voevodsky's split standard triple argument to cohomology theories that can be factorized through ...
- 16.9k
25
votes
2
answers
3k
views
Most significant results in motivic integration theory?
I am thinking about reading a course on motivic integration. I have already read certain introductions to the subject; yet I am not sure that they mention all the significant parts of the theory. So, ...
- 16.9k
35
votes
1
answer
4k
views
Grothendieck's letter to Faltings: On the yoga of motives and the degeneration of Leray spectral sequence
In Grothendieck's letter to Faltings, he writes
There exists at this time a kind of “yoga des motifs”, which is familiar to a handful of initiates, and in some situations provides a firm support for ...
- 40.2k
20
votes
2
answers
5k
views
What does the Jacobian of a curve tell us about the curve?
A natural object in the study of curves is the Jacobian of a curve. What are some natural geometric properties of the curve that the Jacobian encapsulates? In other words, what can the Jacobian tell ...
8
votes
1
answer
958
views
Motives over the complex numbers versus mixed Hodge structures
Let $\mathsf{MM}(\mathbf C)$ be the hypothetical category of mixed motives over the complex numbers, and consider the realization functor $\Phi : \mathsf{MM}( \mathbf C) \to \mathsf{MHS}$ to integral ...
- 40.2k
7
votes
1
answer
759
views
On Deligne's determinant of motives
This is a question about Deligne's conjecture on special values of L-functions. I have to confess that I've never understood the definition of the determinant which is supposed to give the right ...
- 71
11
votes
3
answers
1k
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Motive of CM elliptic curve and modular forms
I am trying to get some insight into the Deligne/Scholl construction of the motive of a modular form. First of all I would like to understand the case of weight two, especially when there is complex ...
- 111
3
votes
1
answer
438
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Virtual Lefschetz motive
Hi there,
I have a question which popped up while reading papers on motives.
Let $V_k$ be the category of (projective) k-varieties, and let $K_0(V_k)$ be the Grothendieck ring of $V_k$; then $\...
- 4,547
3
votes
1
answer
619
views
"Motivic structure on higher homotopy of non-nilpotent spaces" ?
Has anyone an idea where one can read more about Deepam Patel's talk "Motivic structure on higher homotopy of non-nilpotent spaces" http://www.ihes.fr/~abbes/SGA/patel.html ?
Edit/Answer: The video ...
45
votes
2
answers
3k
views
What are the possible motivic Galois groups over $\mathbb Q$?
Let $E$ be a motive over $\mathbb Q$. (I should precise, that by a motive I mean
here a pure motive over $\mathbb Q$, with coefficients in $\mathbb Q$, that I see here as a conjectural object which ...
- 26k
19
votes
2
answers
2k
views
What is the relationship between these two notions of "period"?
The motivation for this question is to understand a recent theorem of Francis Brown which implies that all periods of mixed Tate motives over $\mathbb{Z}$ lie in $\mathcal{Z}[\frac{1}{2\pi i}]$, where ...
- 9,061
3
votes
0
answers
416
views
Chow-Künneth decomposition for hypersurfaces
Short version: is the Chow-Künneth motivic decomposition known for $X \hookrightarrow \mathbb{P}^n_k$ a hypersurface over a field $k$?
Long version: let $M(X)$ be the Chow motive of $X$ with ...
- 31
3
votes
2
answers
375
views
critical values of motives
Hi friends,
I have some questions concerning the critical values of motives, in the sense of Deligne. I will only look at motives of the form $h^i(X)$ where $X$ is a smooth projective algebraic ...
- 31
19
votes
1
answer
2k
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Analogue of Tate or Hodge conjecture for varieties over $\mathbb Q_p$
I've been learning about p-adic Hodge theory recently (I'm a beginner), and I've been wondering about the following question the past couple of weeks. Sorry for the long setup, it's mainly background;...
- 317
6
votes
0
answers
351
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Correspondences of schemes induced by a finite Galois extension
I am trying to do the first exercises of the Mazza-Voevodsky-Weibel book Lecture Notes on Motivic Cohomology, which are some elementary results about correspondences between schemes.
Recall that if $...
0
votes
1
answer
468
views
Pull-back of algebraic cycles under holomorphic maps
Let $f:X \to Y$ be a holomorphic map between two smooth complex projective manifolds. Is there a good notion of pull-back of algebraic cycles by $f$ which preserves degree in the following sense: ...
- 1,040
0
votes
1
answer
450
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Realisation functor
Let k be a field. Is there a realization functor
$DM_{gm}(k,\mathbb{Z}/n)^{op} \to D^b_c(k, \mathbb{Z}/n)$
from category of motives to category of complexes of étale sheaves of $\mathbb{Z}/n$ ...
- 235
1
vote
1
answer
266
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Definition of Hurewicz map relating $SH(k)$ with $DM_\_^{eff}(k)$
In "Motivic Homotopy Theory" on page 153 it is stated that there exists a canonical Hurewicz map relating the motivic stable homotopy category with the category $\operatorname{DM}_\_^{eff}(k)$. ...
- 13
8
votes
1
answer
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Should the etale cohomology of a smooth projective variety (over rationals) be semi-simple; why?
$\DeclareMathOperator{\char}{char}\DeclareMathOperator{\gal}{Gal}$
Let $P$ be a smooth projective variety over a field $K$ (one may certainly assume that $K$ is perfect; the case $K=\mathbb{Q}$ ...
- 16.9k
7
votes
1
answer
498
views
Ring structure for the motivic spectrum/complex that represents singular cohomology?
As the discussion here Is singular cohomology representable by a (Voevodsky's) motivic complex?
shows, the singular cohomology of (smooth) complex varieties is represented by a motivic complex (...
- 16.9k
8
votes
0
answers
244
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Corresponding notion of unramified for motives (or de Rham cohomology)
The etale cohomolgoy of a variety $X$ over a number field $K$ is a Galois representation of $\mathrm{Gal}(\overline K/K)$ with some properties coming from $X$, e.g., it is unramified outside $S$ if $X$...
- 381
2
votes
0
answers
246
views
chow kunneth motivic decomposition for dummies
Hi everybody,
I have just realized that, if I had to explain Chow-Kunneth decomposition for Chow motives to someone who is a newbie of the subject, I would hardly find a way which is far from the ...
- 3,779
2
votes
0
answers
326
views
Voevodsky's 'split standard triple' argument: an explanation; does it work with $Z/nZ$-coefficients?
For varieties over a perfect field (of some characteristic $p$ that could be 0) Voevodsky defines the notion of a 'standard triple' (see http://books.google.ru/books?id=TzUmk87bN9cC&pg=PA85&...
- 16.9k
11
votes
2
answers
1k
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The vanishing of $MGL^{2n+i,n}(X)$; do spectra of smooth projective varieties generate $SH_{l}$?
I have two questions related to the stable motivic homotopy categories of Morel-Voevodsky. The first is probably simple; I wonder what is known on the second one.
For the algebraic cobordism theory $...
- 16.9k