Annali dell''Universita di Ferrara最新文献

In this paper, we have examined the idea of pointwise quasi bi-slant submanifolds of Kenmotsu manifolds and studied warped product pointwise quasi bi-slant submanifolds of Kenmotsu manifolds. We obtain several results on pointwise quasi bi-slant submanifolds of Kenmotsu manifolds and proved the characterization theorem for warped product pointwise quasi bi-slant submanifolds. Also, we provide a non-trivial example of such warped product submanifold.

This paper extends classical approximation theory by establishing Bernstein’s inequality and Jackson’s direct and inverse theorems for the Octonion transform, focusing on functions with a bounded spectrum. Jackson’s inequality bounds the best polynomial approximation of a function based on its smoothness, while Bernstein’s inequality relates the maximum modulus of a polynomial and its derivative on the unit disk. The paper adapts these concepts to the context of octonions.

In this paper, we study the solvability for fractional functional integral equations of Hadamard-type within the Banach algebra (C([1, c]), c > 0). We utilize the Darbo’s fixed point theorem combined with the measure of non-compactness as the main tool. Notably, our existence results encompass and generalize various findings documented in previous literature. To demonstrate the applicability of our approach, we present a detailed example highlighting its effectiveness.

Let R be a prime ring of characteristic different from 2, (nge 1) a fixed integer, C the extended centroid of R, F a generalized skew derivation of R and L a Lie ideal of R. If there exists (0 ne a in R) such that (a(F(xy)-yx)^{n}=0) for all (x,yin L), then L is central, unless R satisfies the standard polynomial identity (s_4(x_1, ldots , x_4)).

The main crux of this paper is to introduce a new integral transform called the multidimensional Hankel–Gabor transform and to give some new results related to this transform as Plancherel’s, Parseval’s, inversion and Calderón’s reproducing formulas. Next, we analyse the concentration of this transform on sets of finite measure and we give uncertainty principle for orthonormal sequences and Donoho–Stark’s type uncertainty principle. Last, we introduce a new class of pseudo-differential operator ({mathscr {L}}_{u,v}(sigma )) called localization operator which depend on a symbol (sigma ) and two functions u and v, we give a criteria in terms of the symbol (sigma ) for its boundedness and compactness, we also show that this operator belongs to the Schatten-Von Neumann classes (S^p) for all (p in [1; +infty ]) and we give a trace formula.

We compute the homogeneous ideals of varieties, in a projective space of tensors, associated to different choices of the Boolean operators that describe the decision process in small neural networks. We prove that, starting with networks with three nodes, the varieties associated to different Boolean operators are all distinct.

We investigate some hydrodynamic stability problems in the context of the Navier–Stokes–Voigt equations. It is pointed out that one should regard the usual set of equations known as the Navier–Stokes–Voigt equations as being the Navier–Stokes equations to which a regularizing term has been added. We investigate other models which have features very similar to the Navier–Stokes–Voigt equations, but which arise from proper continuum thermodynamic approaches, including employing an objective time derivative rather than simply the Laplacian of the partial time derivative of the velocity field. It is shown that in some cases, particularly those connected to straightforward thermal convection studies, the linear theory of the more physically based models reduces to that of the classical Navier–Stokes–Voigt theory. However, these are special problems and we also display other problems where the generalized theories based on continuum mechanics principles lead to very different results from what one finds with traditional Navier–Stokes–Voigt theory. Finally, two further models pertaining to Navier–Stokes–Voigt theory which were introduced by Oskolkov are investigated.

In this note, we generalize Cline’s formula for some new generalized inverses such as strong Drazin inverse, generalized strong Drazin inverse, Hirano inverse and generalized Hirano inverse. As a particular case, some recent results on this subject are recovered.

The paper presents a general model of quasi-linear parabolic equations with variable exponents for the source and dissipative term types

When (p(x)ge m(x)ge 2), the matrix (textrm{L}(t)) is both positive definite and bounded, while the function g is continuously differentiable and decays over time. The paper shows that the blow-up result occurs at two different finite times and provides an upper bound for the blow-up time. Finally, it establishes that the energy function decays globally for solutions, with both positive and negative initial energy.

In this paper we have define ((alpha ,beta ))-biderivation on triangular algebra (mathcal {A}) and characterize some result on triangular algebras. Apart from that, in Theorem 3.5, we show that any map on (mathcal {A} times mathcal {A} rightarrow mathcal {A}) becomes ((alpha ,alpha ))-biderivation after imposing certain conditions.