6,596 research outputs found
The valuation criterion for normal basis generators
If is a finite Galois extension of local fields, we say that the
valuation criterion holds if there is an integer such that every
element with valuation generates a normal basis for .
Answering a question of Byott and Elder, we first prove that holds if
and only if the tamely ramified part of the extension is trivial and
every non-zero -submodule of contains a unit. Moreover, the integer
can take one value modulo only, namely , where
is the valuation of the different of . When has positive
characteristic, we thus recover a recent result of Elder and Thomas, proving
that is valid for all extensions in this context. When
\char{\;K}=0, we identify all abelian extensions for which is
true, using algebraic arguments. These extensions are determined by the
behaviour of their cyclic Kummer subextensions
The role of affective and cognitive attitude extremity in perceived viewpoint diversity exposure
The current study examines the role of affective and cognitive attitude extremity on perceived exposure to diverse political viewpoints and investigates the possibility of a âprimacy of affect.â Based on a multi-level analysis of panel survey data, we show that people with extreme attitudes toward immigrants experience less viewpoint diversity and that this tendency is especially pronounced for affective attitude extremity. However, even those holding extreme attitudes do not find themselves in issue-specific echo chambers, that is, they still encounter relatively diverse sets of viewpoints
Galois representations and Galois groups over Q
In this paper we generalize results of P. Le Duff to genus n hyperelliptic
curves. More precisely, let C/Q be a hyperelliptic genus n curve and let J(C)
be the associated Jacobian variety. Assume that there exists a prime p such
that J(C) has semistable reduction with toric dimension 1 at p. We provide an
algorithm to compute a list of primes l (if they exist) such that the Galois
representation attached to the l-torsion of J(C) is surjective onto the group
GSp(2n, l). In particular we realize GSp(6, l) as a Galois group over Q for all
primes l in [11, 500000].Comment: Minor changes. 13 pages. This paper contains results of the
collaboration started at the conference Women in numbers - Europe, (October
2013), by the working group "Galois representations and Galois groups over Q
A Consistent Diffusion-Based Algorithm for Semi-Supervised Graph Learning
The task of semi-supervised classification aims at assigning labels to all
nodes of a graph based on the labels known for a few nodes, called the seeds.
One of the most popular algorithms relies on the principle of heat diffusion,
where the labels of the seeds are spread by thermoconductance and the
temperature of each node at equilibrium is used as a score function for each
label. In this paper, we prove that this algorithm is not consistent unless the
temperatures of the nodes at equilibrium are centered before scoring. This
crucial step does not only make the algorithm provably consistent on a block
model but brings significant performance gains on real graphs.Comment: arXiv admin note: substantial text overlap with arXiv:2008.1194
Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms
This review describes strategies for the chemical synthesis of xenicane diterpenoids and structurally related metabolites. Selected members from the four different subclasses of the Xenia diterpenoid family, the xenicins, xeniolides, xeniaphyllanes and xeniaethers, are presented. The synthetic strategies are discussed with an emphasis on the individual key reactions for the construction of the uncommon nine-membered carbocycle which is the characteristic structural feature of these natural products. Additionally, the putative biosynthetic pathway of xenicanes is illustrated
Synthesis of Xenia diterpenoids and related metabolites isolated from marine organisms
This review describes strategies for the chemical synthesis of xenicane diterpenoids and structurally related metabolites. Selected members from the four different subclasses of the Xenia diterpenoid family, the xenicins, xeniolides, xeniaphyllanes and xeniaethers, are presented. The synthetic strategies are discussed with an emphasis on the individual key reactions for the construction of the uncommon nine-membered carbocycle which is the characteristic structural feature of these natural products. Additionally, the putative biosynthetic pathway of xenicanes is illustrated
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