More on convolution of Riemannian manifolds.
Submanifolds with parallel mean curvature vector play important roles in differential geometry, theory of harmonic maps as well as in physics. Spatial surfaces in 4D Lorentzian space forms with parallel mean curvature vector were classified by B. Y. Chen and J. Van der Veken in [9]. Recently, spatial surfaces with parallel mean curvature vector in arbitrary pseudo-Euclidean spaces are also classified in [7]. In this article, we classify spatial surfaces with parallel mean curvature vector in pseudo-Riemannian...
A Lorentz surface of an indefinite space form is called a parallel surface if its second fundamental form is parallel with respect to the Van der Waerden-Bortolotti connection. Such surfaces are locally invariant under the reflection with respect to the normal space at each point. Parallel surfaces are important in geometry as well as in general relativity since extrinsic invariants of such surfaces do not change from point to point. Recently, parallel Lorentz surfaces in 4D neutral pseudo Euclidean...
Vengono date varie informazioni concernenti la distribuzione dei valori di due degli invarianti di deformazione di una varietà di Bochner-Kaehler (§1, Theor. 1), facendone poi varie applicazioni (§4).
Vengono date condizioni sufficienti affinché una varietà compatta di Kaehler o coomologicamente di Einstein-Kaehler sia einsteiniana (Teorema 1, 2); se ne deducono condizioni assicuranti che un'intersezione completa in uno spazio proiettivo complesso risulti uno spazio lineare od un'iperquadrica (Teorema 3).
Vengono classificate le superficie di uno spazio euclideo m-dimensionale dotate di connessione normale piatta, con lo studio di opportune equazioni alle derivate parziali. Alcuni casi particolari vengono approfonditi, facendo varie applicazioni.
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