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16 votes
1 answer
3k views

Tate twists and cohomology of $\mathbf{P}^1$

I was wondering if anyone could give me some intuition as to why, for a smooth projective variety $X$ over $\mathbf{C}$ of complex dimension $d$, the Tate twist on $H^n(X(\mathbf{C}),\mathbf{Z})$ to ...
user avatar
14 votes
1 answer
746 views

Can there exist Chow motives/motivic cohomology for compact Kähler manifolds?

Can there exist a 'reasonable' extension of the (higher) Chow groups of complex smooth projective algebraic varieties to functors on the category of compact Kähler manifolds? Are there any ...
Mikhail Bondarko's user avatar
10 votes
2 answers
1k views

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'...
Andres Garcia's user avatar
9 votes
1 answer
643 views

Torsion in Deligne cohomology

Let $X$ be a smooth projective complex analytic space, $i,p\ge 0$ integers, $\mathbf{Z}(p)_{\mathcal{D}}$ the Deligne complex of $X$, $H^i_{\mathcal{D}}(X,\mathbf{Z}(p))$ its hypercohomology. What ...
user avatar
8 votes
1 answer
492 views

Motives of complex-analytic spaces

In any setting where we have a notion of space and a notion of cohomology theory, we in principle could ask "what are motives in this setting?". In some settings the question can be interesting (i.e. ...
user avatar
8 votes
1 answer
432 views

Finiteness aspects of Deligne cohomology

Say $X$ is a smooth projective variety over $\mathbf{C}$, and $\mathcal{X} = X^{\rm an}$ its $\mathbf{C}$-analytic space. For what integers $i,d$ is the Deligne cohomology $H^i_{\mathcal{D}}(\mathcal{...
user avatar
7 votes
1 answer
474 views

Motivic $\mathbf{Z}(1)$

I know that the Bloch higher Chow complex, $\mathbf{Z}(i)_{\mathcal{M}}$, on a smooth scheme over a field $k$, reads, in degree $1$: $$\mathbf{Z}(1)_{\mathcal{M}}\simeq\mathbf{G}_m[-1].$$ How to see ...
user avatar
6 votes
1 answer
1k views

Intuition for polarized Hodge structures

A Hodge structure can be defined as a real, algebraic representation of the Deligne torus ${Res}^\mathbb{C}_{\mathbb{R}}\mathbb{G}_m$. Coming from Kahler manifolds the intuition for this is clear. The ...
Saal Hardali's user avatar
  • 7,789
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 ...
user avatar
2 votes
1 answer
164 views

Full lattice images and Hodge decomposition

Let $X$ be a smooth and proper complex analytic space, or a Kahler complex manifold. Is the image $\Lambda$ of the finitely generated abelian group $H^{2i}(X,\mathbf{Z})$ into $J := H^{2i}(X,\mathbf{C}...
user avatar
2 votes
0 answers
483 views

Absolute Hodge cycles over $\mathbf{Q}$

In the 1986 notes by Milne "Hodge cycles on abelian varieties", Deligne defines the notion of absolute Hodge cycles. For a smooth projective variety defined over $k\subset\mathbf{C}$ non ...
user avatar
2 votes
0 answers
304 views

Should all cohomology theories have a smooth proper base change

Let $H$ be a cohomology theory with respect to some Grothendieck topology (e.g. Zariski, analytic, etale, fppf, Nisnevich, etc.) Does H satisfy smooth proper base? If yes, does this mean that "...
Ciro's user avatar
  • 119