Tagged Questions

10
votes
2answers
266 views

A_infinity structure on cohomology and the weight filtration

Let $X$ be a complex algebraic variety. The rational cohomology of $X(\mathbb{C})$ carries a canonical filtration called the weight filtration. It also carries a canonical equiva …
0
votes
0answers
36 views

semicontinuity results for weights

Let $f:X\rightarrow Y$ a proper flat map between smooth schemes over a finite field $k$ and the base is integral. For an integer $i$, we consider the the l-adic sheaf $R^{i}f_{*}\ …
0
votes
0answers
32 views

Weight an output of a function based on input

Hi I am creating an android app that will generate a cycling route for users using a route finder. I am trying to allow the user to either prefer distance or routes with cyclelane …
4
votes
2answers
236 views

Weights of restricted modules of some Cartan type Lie algebras

Let $L$ be a simple Lie algebra of Cartan type of absolute toral rank 2 over an algebraically closed field $\mathbb{F}$ of characteristic $p\geq 5$. Denote by $L_{[p]} $ the minima …
1
vote
0answers
133 views

Universal Correlation measure — ranking correlations

I have time series data of experimental observations for two related processes. I want to measure correlation for use in further analysis. Correlation of the series changes over t …
2
votes
1answer
275 views

Which (reducible) projective varieties could be presented as ‘relatively smooth’ hyperplane sections of irreducible (normal) ones?

Are there any restrictions known on a (complex reducible) projective variety $Y$ that can be presented as $Z\cap H$, where $Z$ is a normal (or just irreducible) closed subvariety o …
2
votes
0answers
208 views

Does Artin’s vanishing hold for ‘$E_2$-weight pieces’ for (torsion) cohomology of affine varieties?

Let $X$ be an affine variety of dimension $n$ (say, over complex numbers). Then Artin's vanishing theorem yields: both singular and etale cohomology $H^i(X):=H^i(X,\mathbb{Z}/l\mat …
6
votes
1answer
345 views

Does intersection pairing on `$IH^*(X)$` agree with cup-product on `$H^*(X)$`?

Let $X$ be a proper singular variety over $k=\overline{\mathbb F}_p,$ irreducible of dimension $d.$ Let $H^*(X)$ and $IH^*(X)$ be the $l$-adic cohomology groups and $l$-adic inters …
1
vote
1answer
68 views

weighted to centre mean

I'm not even sure if what I want to do is a good idea but I figure I'll experiment and see. I have two predicted ratings in the range of 1-5 based on two different algorithms for …
1
vote
0answers
111 views

A Weyl invariance constructed from Clebsch-Gordan Coefficients.

Let $V$ and $\tilde{V}$ be irreducible representations of SU(N) with tensor decomposition: \begin{equation} V \otimes \tilde{V} = \bigoplus_i U_i \end{equation} \noindent were $ …
5
votes
4answers
416 views

Smooth in codimension-k and the weight filtration

Let $X$ be an algebraic variety. Then $H_{et}^k(X)$ has a filtration whose associated graded pieces are labeled by "weights", certain integers between $0$ and $2k$. If $X$ is smoot …
1
vote
2answers
194 views

Maximizing the ratio of (weigthed sum)/sqrt(variance_weighted_sum)

I have a weighted sum, weighted sum = w1*mu1 + (1-w1)*mu2 with variance weighted sum = (w1^2)*var1 + ((1-w1)^2)*var2 + 2*w1*(1-w1)*cov in which mu1 = mean 1; mu2 = mean 2; v …
7
votes
2answers
542 views

Which statements in section 5 of BBD will fail if we consider $\mathbb{Q}_l$-adic sheaves there?

A stupid question: which statements in section 5 of BBD will fail if we replace $\overline{\mathbb{Q}_l}$-sheaves by just $\mathbb{Q}_l$-ones? I am especially interested in Proposi …
3
votes
1answer
572 views

Do Deligne’s decalage and two filtrations for mixed Hodge complexes have a conceptual explanation?

As far as I understood, there are two way to assign weights to a mixed Hodge complex (a way that does not depend on shifts, and another one that does). There is a clever way to rel …
3
votes
2answers
508 views

In what setting does one usually define mixed sheaves and weights for them?

In BBD mixed sheaves and weights for them were only defined for ($\overline{\mathbb{Q}_l}$-)sheaves over a variety $X_0$ defined over a finite field $F$. Weights start to behave be …

1 2 next
15 30 50 per page