Le Matematiche (Dipartimento di Matematica e Informatica, Università degli Studi di Catania)
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The b-Chromatic Number of Star Graph Families
Get PDFIn this paper, we investigate the b-chromatic number of central graph, middle graph and total graph of star graph, denoted by C(K1,n), M(K1,n) and T(K1,n) respectively. We discuss the relationship between b-chromatic number with some other types of chromatic numbers such as chromatic number, star chromatic number and equitable chromatic number
Periodic solutions of the forced pendulum: classical vs relativistic
Get PDFThe paper surveys and compares some results on the existence and multiplicity of T-periodic solutions for the forced classical pendulum equation, the forced p-pendulum equation and the forced relativistic pendulum equation
On the Hilbert series of vertex cover algebras of Cohen-Macaulay bipartite graphs
Get PDFWe study the Hilbert function and the Hilbert series of the vertex cover algebra A(G), where G is a Cohen-Macaulay bipartite graph
A note on quasi-polarized surfaces of general type whose sectional genus is equal to the irregularity
Get PDFLet be a quasi-polarized surface.In our previous papers, we studied with , and .Here denotes the sectional genus of .In this note, we give the classification of quasi-polarized surfaces of this type completely
Monotone solutions for nonconvex functional differential inclusions of second order with Caratheodory perturbation
Get PDFWe give sufficient conditions to assure the existence of a monotone solution for a functional differential inclusions of second order with Caratheodory perturbation. No convexity condition is involved on the values of the right hand side in the construction. This work generalizes some a recent papers, for example [1,13,15]
Three nontrivial solutions for Neumann problems resonant at any positive eigenvalue
Get PDFWe consider a semilinear Neumann problem with a parametric reaction which has a concave term and a perturbation which at ±∞ can be resonant with respect to any positive eigenvalue. Using variational methods based on the critical point theory and Morse theory, we show that there exists a critical parameter value λ ∗ > 0 such that if λ ∈(0, λ ∗ ), then the problem has at least three nontrivial smooth solutions
Variational-hemivariational inequalities with nonhomogeneous Neumann boundary condition
Get PDFThe aim of this paper is the study of variational-hemivariational inequalities with nonhomogeneous Neumann boundary condition. Sufficient conditions for the existence of a whole sequence of solutions which is either unbounded or converges to zero are proved. For homogeneous Neumann boundary condition, results of this type have been obtained in Marano and Motreanu [3]. Our approach is based on abstract nonsmooth critical point results given in [3]. The applicability of our results is demonstrated by providing two verifiable criteria which address problems with nonsmooth potential and nonzero Neumann boundary condition
An application of Phragmén-Lindelöff\u27s Theorem in an abstract elliptic equation of second order
Get PDFIn this paper we prove that Theorem of Phragmén-Lindelöf’s can be applied in abstract elliptic equation of second order
Some infinite classes of asymmetric nearly Hamiltonian snarks
Get PDFWe determine the full automorphism group of each member of three infinite families of connected cubic graphs which are snarks. A graph is said to be nearly hamiltonian if it has a cycle which contains all vertices but one. We prove, in particular, that for every possible order n ≥ 28 there exists a nearly hamiltonian snark of order n with trivial automorphism group
Lorentzian Beltrami-Euler formula and generalized Lorentzian Lamarle formila in R_1^n
Get PDFIn this paper, the sectional curvature of non-degenerate tangent sections of time-like ruled surface with the central ruled surface in n-dimensional Minkowski space, R_1^n is studied. The relationship between normal sectional curvature and the principal sectional curvatures of non-degenerate tangent sections of time-like ruled surfaces is obtained andcalled as Lorentzian Beltrami-Euler formula. Moreover, the relationship between the Gaussian curvature and the principal distribution parameter of the non-degenerate tangent sections of time-like ruled surfaces is obtained and called as generalized Lorentzian Lamarle formula