1,720,970 research outputs found
Una estensione del concetto di midpoint convessità per multifunzioni
No full textThis note starts from recent research of K. Nikodem [Aequationes Math. 33 (1987), no. 1, 46–
56; MR0901799 (88h:90171)] on the continuity of convex multifunctions, whose results are extended. Here the authors introduce the concept of midpoint convexity for multifunctions and give conditions for lower semicontinuity. A similar theorem holds for midpoint concavity. From these theorems there follows a condition of continuity for midpoint additive multifunctions
Sulle semicontinuità inferiore e superiore di una multifunzione
No full textIn this note we obtain several relations between a multifunction F and the relative border-multifunction, concerning the lower semicontinuity (topological or metric), the upper semicontinuity (topological or metric) and the continuity (topological or metric). These results contain or extend various results stated by M. D. P. M. Marques in 1983,
Moreover, we prove a sufficient condition that extends a proposition of M. Valadier
Sull'esistenza di punti fissi per multifunzioni a grafo debolmente chiuso
No full textIn this note are obtained two fixed point theorems for weakly closed graph multimaps. The above theorems generalize well-known results of C. J. Himmelberg and A. Idzik
Some results on stability and on characterization of K-convexity of set-valued functions
No full textThe authors establish interesting results concerning the Ulam-Hyers-type stability of K-convex set-valued functions and the characterization of K-convex set-valued functions, where K is a convex cone in a real topological vector space. The main results are given by Theorem 1 and Corollary 1. These represent contributions to this field of convex analysis, founded by D. H. Hyers and S. M. Ulam
Heteroclinic solutions of boundary value problems on the real line involving general nonlinear differential operators
No full textWe discuss the solvability of the following strongly nonlinear
non-autonomous boundary-value problem:
(a(x(t))Φ(x (t)))' = f (t, x(t), x (t)) a.e. t ∈ R
x(−∞) = ν − , x(+∞) = ν + with ν − < ν + , where Φ : R → R is a general increasing homeomorphism, with Φ(0) = 0, a is a positive, continuous function and f is a Carathe ́dory nonlinear function. We provide some sufficient conditions for the solvability, which turn out to be optimal for a large class of problems. In particular, we highlight the role played by the behavior of f (t, x, ·) and Φ(·) as y → 0 related to that of f (·, x, y) as |t| →+∞.
We also show that the dependence on x, both of the differential operator
and of the right-hand side, does not influence in any way the existence
or non-existence of solutions
On the solvability of a boundary value problem on the real line
Full text linkAbstract
We investigate the existence of heteroclinic solutions to a class of nonlinear differential equations
(
a
(
x
)
Φ
(
x
′
(
t
)
)
)
′
=
f
(
t
,
x
(
t
)
,
x
′
(
t
)
)
,
a
.
e
.
t
∈
ℝ
governed by a nonlinear differential operator Φ extending the classical p- Laplacian, with right-hand side f having the critical rate of decay -1 as |t| → +∞, that is
f
(
t
,
⋅
,
⋅
)
≈
1
t
. We prove general existence and non-existence results, as well as some simple criteria useful for right-hand side having the product structure f(t, x, x') = b(t, x)c(x, x').
Mathematical subject classification: Primary: 34B40; 34C37; Secondary: 34B15; 34L30.</jats:p
On a class of evolution equations without convexity
No full textThe authors consider perturbations of equations of subgradient type . The first class of examples includes operators A being the subdifferential of a nonconvex function φ -monotone of order 2 . The second class of problems contains equations perturbed by a nonconvex-valued operator
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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