Results 221 to 230 of about 724,503 (248)

The K(Pi, 1)-conjecture for the affine braid groups

2003
The authors prove that the complement of the hyperplane arrangement associated to the complexified action of a Euclidean reflection group of type \(\widetilde A_n\) is a \(K(\pi,1)\) space. This is done using the fact that the associated affine braid group \(\widetilde{\mathcal A}\) can be embedded in a finite type Artin braid group.
Charney, Ruth, Peifer, David
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Printed Circuit Board Inspection System PI/1

SPIE Proceedings, 1989
An automatic printed circuit board (PCB) inspection system called PI/1, is described in this paper. The system can inspect PCB artwork and inner layers to find trace faults such as open circuits, short circuits, pin holes, fine lines and narrow line spaces. PI/1 uses a line scan camera with 1024 pixels resolution to take images.
Shiaw-Shian Yu, Wen-Chin Cheng, Chris S. C. Chiang   +2 more
openaire   +1 more source

An ionospheric origin for Pi 1 micropulsations

Planetary and Space Science, 1976
Abstract Cosmic noise absorption pulsation events observed with fast response riometers at Macquarie Island in the southern auroral zone have almost always been accompanied by Pi 1 micropulsations. A cross-spectral analysis of fast response riometer data and vertical component induction magnetometer data for one such event showed that, after the low ...
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Type Pi 1?2 magnetic field pulsations

Space Science Reviews, 1981
The relationships of type Pi (broadband) pulsations to various other substorm-related phenomena are reviewed. Several of the more popular mechanisms for the origin of Pi activity are discussed in the light of the observations. There is only one mechanism in sight that tentatively accounts for observed characteristics of Pi 1–2 activity at auroral oval ...
R.R. Heacock, R.D. Hunsucker
openaire   +1 more source

SMOOTH KNOTS IN A MANIFOLD OF HOMOTOPY TYPE $ K(\pi,1)$

Mathematics of the USSR-Izvestiya, 1975
The author studies the set of smooth isotopy classes of embeddings of a sphere in a manifold having homotopy type , where . He obtains an explicit expression for in terms of the group and the well-known Haefliger groups of knots and finite links of the sphere in?.Bibliography: 7 items.
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$${\mathbb{A}}^{1}$$ -Coverings, $${\pi }_{1}^{{\mathbb{A}}^{1} }({\mathbb{P}}^{n})$$ and $${\pi }_{1}^{{\mathbb{A}}^{1} }(S{L}_{n})$$

2012
A simplicial covering \(\mathcal{Y}\rightarrow \mathcal{X}\)is a morphism of spaces which has the unique right lifting property with respect to simplicially trivial cofibrations.
openaire   +1 more source

The $ K(\pi,1)$-property for smooth marked curves over finite fields

Izvestiya: Mathematics, 2015
In recent papers (for instance: [Doc. Math., J. DMV 12, 441--471 (2007; Zbl 1169.11048); J. Reine Angew. Math. 640, 203--235 (2010; Zbl 1193.14041)]) the second author studied the ``\(K(\pi, 1)\)-property for \(p\)'' (the definition which uses a Hochschild-Serre spectral sequence is given in \S 1.1 of the present paper) for arithmetic curves whose ...
Lebacque, Phillipe, Schmidt, Alexander
openaire   +1 more source