Search results for "archimede"
showing 10 items of 18 documents
Self-Assembly of Water-Mediated Supramolecular Cationic Archimedean Solids
2013
Understanding the self-assembly of small structural units into large supramolecular assemblies remains one of the great challenges in structural chemistry. We have discovered that tetrahedral supramolecular cages, exhibiting the shapes of Archimedean solids, can be self-assembled by hydrogen bonding interactions using tricationic N-donors (1 or 2) in cooperation with water (W). Single crystal X-ray analysis shows that cage (2)4(W)6, assembled in an aqueous solution of cation 2 and KPF6, consists of four tripodal trications linked by six water monomers and resembles the shape of a truncated tetrahedron. Similarly, cage (1)4(W6)4 spontaneously self-assembles in an aqueous solution of cation 1…
Prefazione. Filosofia e scienza in Domenico Scinà
2016
Nel corso della storia della cultura occidentale possiamo riscontrare filosofi che furono anche poeti (Empedocle, Parmenide) o poeti che furono anche filosofi (Omero, Esiodo). Perciò le discipline il più delle volte non sono facilmente delimitabili, così come accade leggendo le Purificazioni di Empedocle o il poema Sulla natura di Parmenide. Nell’ambito della letteratura troviamo “briciole” di poesia che hanno determinato suggestioni e riflessioni non marginali: in questo caso la memoria suggerisce la rilettura de Il lamento di Danae del poeta greco Simonide di Ceo o de L’infinito del poeta italiano Giacomo Leopardi. In tal senso potremmo soffermarci sulla reinterpretazione che delle traged…
Some new fixed point results in non-Archimedean fuzzy metric spaces
2013
In this paper, we introduce the notions of fuzzy $(\alpha,\beta,\varphi)$-contractive mapping, fuzzy $\alpha$-$\phi$-$\psi$-contractive mapping and fuzzy $\alpha$-$\beta$-contractive mapping and establish some results of fixed point for this class of mappings in the setting of non-Archimedean fuzzy metric spaces. The results presented in this paper generalize and extend some recent results in fuzzy metric spaces. Also, some examples are given to support the usability of our results.
Fixed points in weak non-Archimedean fuzzy metric spaces
2011
Mihet [Fuzzy $\psi$-contractive mappings in non-Archimedean fuzzy metric spaces, Fuzzy Sets and Systems, 159 (2008) 739-744] proved a theorem which assures the existence of a fixed point for fuzzy $\psi$-contractive mappings in the framework of complete non-Archimedean fuzzy metric spaces. Motivated by this, we introduce a notion of weak non-Archimedean fuzzy metric space and prove that the weak non-Archimedean fuzzy metric induces a Hausdorff topology. We utilize this new notion to obtain some common fixed point results for a pair of generalized contractive type mappings.
The contributions of Hilbert and Dehn to non-Archimedean geometries and their impact on the Italian school
2007
In this paper we investigate the contribution of Dehn to the development of non- Archimedean geometries. We will see that it is possible to construct some models of non- Archimedean geometries to prove the independence of the continuity axiom and we will study the interrelations between Archimede’s axiom and Legendre‘s theorems. Some of these interrelations were studied also by Bonola who was one of the very few italian scholars to really appreciate Dehn’s work. We will see that, if Archimede’s axiom does not hold, the hypothesis on the existence and the number of parallel lines through a point is not related to the hypothesis on the sum of the inner angles a triangle. Hilbert himself retur…
Some models of geometries after Hilbert’s Grundlagen
2010
Sono descritti alcuni dei principali modelli di geometrie non desarguesiane e non archimedee Abstract: We investigate the contribution of Max Dehn to the development of non-Archimedean geometries and the contribution of his student Ruth Moufang to the development of non-Desarguesian geometries.
Laboratorio collegato al bando UMI Premio Archimede
2013
Viene descritta un'attività laboratoriale svolta nell'ambito del Progetto Lauree Scientifiche, collegata al Bando UMI sul Premio Archimede.
Some integral type fixed point theorems in Non-Archimedean Menger PM-Spaces with common property (E.A) and application of functional equations in dyn…
2013
In this paper, we prove some integral type common fixed point theorems for weakly compatible mappings in Non-Archimedean Menger PM-spaces employing common property (E.A). Some examples are furnished which demonstrate the validity of our results. We extend our main result to four finite families of self-mappings employing the notion of pairwise commuting. Moreover, we give an application which supports the usability of our main theorem.
Best Proximity Point Results in Non-Archimedean Fuzzy Metric Spaces
2013
We consider the problem of finding a best proximity point which achieves the minimum distance between two nonempty sets in a non-Archimedean fuzzy metric space. First we prove the existence and uniqueness of the best proximity point by using di fferent contractive conditions, then we present some examples to support our best proximity point theorems.
Semi-compatible and reciprocally continuous maps in weak non-Archimedean Menger PM-spaces
2012
In this paper, we introduce semi-compatible maps and reciprocally continuous maps in weak non-Archimedean PM-spaces and establish a common fixed point theorem for such maps. Moreover, we show that, in the context of reciprocal continuity, the notions of compatibility and semi-compatibility of maps become equivalent. Our result generalizes several fixed point theorems in the sense that all maps involved in the theorem can be discontinuous even at the common fixed point.