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Integral formula for secantoptics and its application

Witold Mozgawa, Magdalena Skrzypiec (2012)

Annales UMCS, Mathematica

Some properties of secantoptics of ovals defined by Skrzypiec in 2008 were proved by Mozgawa and Skrzypiec in 2009. In this paper we generalize to this case results obtained by Cieślak, Miernowski and Mozgawa in 1996 and derive an integral formula for an annulus bounded by a given oval and its secantoptic. We describe the change of the area bounded by a secantoptic and find the differential equation for this function. We finish with some examples illustrating the above results.

Integral formulas related to wave fronts

Sergeĭ Anisov (1999)

Banach Center Publications

In the first section of the paper we study some properties of oriented volumes of wave fronts propagating in spaces of constant curvature. In the second section, we generalize to an arbitrary isometric action of a Lie group on a Riemannian manifold the following principle: an extra pression inside of a ball does not move it.

Introduction à l’étude globale des tissus sur une surface holomorphe

Vincent Cavalier, Daniel Lehmann (2007)

Annales de l’institut Fourier

Beaucoup de concepts sur les tissus n’ont été étudiés que localement. Il apparaît que certains d’entre eux se laissent globaliser, mais pas toujours de façon immédiate. Le premier objectif de cet article est de préciser à chaque fois ce qu’il en est, et de mettre en place les outils utiles à une étude globale des tissus sur une surface holomorphe M arbitraire, et en particulier sur le plan projectif complexe 2 . Certains concepts nouveaux vont alors apparaître, tels le type (ou le degré si M = 2 ), la...

Invariance groups of relative normals

Thomas Binder, Martin Wiehe (2005)

Banach Center Publications

We investigate a two-parameter family of relative normals that contains Manhart's one-parameter family and the centroaffine normal. The invariance group of each of these normals is classified, and variational problems are studied. The results are Euler-Lagrange equations for the hypersurfaces that are critical with respect to the area functionals of the induced and semi-Riemannian volume forms and a classification of the critical hyperovaloids in the two-parameter family.

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