Showing papers by "Matej Bel University published in 2007"
TL;DR: In this article, a generalized Romberg differentiation procedure for numerical evaluation of first-order and higher-order derivatives is proposed, which is more robust in treating rounding errors, as shown by numerical tests.
Abstract: A generalized Romberg differentiation procedure decreasing truncation errors for numerical evaluation of first-order as well as higher-order derivatives is proposed. In comparison with the original Romberg method the higher-order terms are eliminated more efficiently. Moreover, the generalized scheme is more robust in treating rounding errors, as shown by numerical tests. The proposed method can find a wide range of applications including the evaluation of electronic and vibrational (hyper)polarizabilities.
59 citations
TL;DR: A unified account of a number of dual category equivalences of relevance to the theory of canonical extensions of distributive lattices is presented, including that due to B. Banaschewski between the categories of Boolean topological bounded distributives and the category of ordered sets.
Abstract: This paper presents a unified account of a number of dual category equivalences of relevance to the theory of canonical extensions of distributive lattices. Each of the categories involved is generated by an object having a two-element underlying set; additional structure may be algebraic (lattice or complete lattice operations) or relational (order) and, in either case, topology may or may not be included. Among the dualities considered is that due to B. Banaschewski between the categories of Boolean topological bounded distributive lattices and the category of ordered sets. By combining these dualities we obtain new insights into canonical extensions of distributive lattices.
22 citations
TL;DR: A possible extension ofygralak's axiomatic theory of scalar cardinalities of fuzzy sets with finite support to interval-valued fuzzy set theory is presented and some properties of these cardinalities using t-norms, t-conorms and negations are studied.
20 citations
TL;DR: In this paper, a hadronic kinetic model was proposed to describe the production of strange particles in ultrarelativistic nuclear collisions in the energy domain of SPS, and the model was tested on other types of data in order to verify the hypothesis that deconfinement sets in at lowest SPS energies.
Abstract: We construct a hadronic kinetic model which describes production of strange particles in ultrarelativistic nuclear collisions in the energy domain of SPS. We test this model on the description of the sharp peak in the excitation function of the multiplicity ratio K+/π+ and demonstrate that the hadronic model reproduces these data rather well. The model thus must be tested on other types of data in order to verify the hypothesis that deconfinement sets in at lowest SPS energies.
17 citations
TL;DR: The functional envelope of a dynamical system always contains a copy of the original system as discussed by the authors, and the functional envelope can be seen as a special case of the functional difference equation.
Abstract: If (X, f) is a dynamical system given by a compact metric space X and a continuous map f : X → X then by the functional envelope of (X, f) we mean the dynamical system (S(X), Ff) whose phase space S(X) is the space of all continuous selfmaps of X and the map Ff : S(X) → S(X) is defined by Ff() = f for any S(X). The functional envelope of a system always contains a copy of the original system.Our motivation for the study of dynamics in functional envelopes comes from semigroup theory, from the theory of functional difference equations and from dynamical systems theory. The paper mainly deals with the connection between the properties of a system and the properties of its functional envelope. Special attention is paid to orbit closures, ω-limit sets, (non)existence of dense orbits and topological entropy.
16 citations
TL;DR: Decomposition theorem (representation by cuts) is proved for “neither less nor equal” cuts and collection of all cuts of any lattice-valued fuzzy set form a complete lattice under inclusion.
12 citations
TL;DR: Inverse electron-demand Diels-Alder reactions of 1,3,5-triazines and 2-aminopyrroles are facilitated by electron-withdrawing groups (EWG) on both reactants.
Abstract: Inverse-electron demand Diels-Alder reactions of 1,3,5-triazines and 2-aminopyrroles are facilitated by electron-withdrawing groups (EWG) on both reactants. Whereas HOMO-LUMO calculations predict that EWG on 2aminopyrroles should lower the relative rate of reaction. This apparent contradiction can be explained if the reaction cascade is under equilibrium control with at least one reversible step. Introduction The 2-aminopyrrole ring is very electron rich. Only derivatives with electron withdrawing substituents are stable.' Simple 2-aminopyrroles, without further substitution on the ring, have been isolated as their tetraphenylborate salts. Addition of triethylamine (TEA) to solutions of the tetraphenylborate salts can be used to generate simple 2aminopyrroles in situ. In this manner the Diels-Alder reaction of 2-aminopyrroles with dimethyl acetylenedicarboxylate (DMAD) was attempted but Michael addition occurred instead. Dang and co-workers have examined the inverse electron-demand Diels-Alder (IDA) reactions of 1,3,5-triazines with 4-cyano-2-aminopyrroles. ' A cascade reaction took place with the formation of pyrrolo[2,3-if]pyrimidines. Theoretical studies of this process have also appeared. In this communication we examine how the nature of the substituents on the 1,3,5-triazines and 2-aminopyrroles affect the reaction. Ε Ν Ε f \\ π Τ N X n h 2 + N Y N R Ε Ε Ν R Η,Ν Ε -νη 3 | -ECN* γ!Λ ε Ν ι R 2a (E=C02Et) 2b (E=CF3) 3(R=CH3; E=C02Et) 4(R=C2H5; E=C02Et) 5(R=f-C4H9; E=C02Et) 6(R=CH3; E=CF3) 7(R=C2H5; E=CF3) 8(R=f-C4H9; E=CF3)
11 citations
TL;DR: When a good leaving group is present in the heteroaromatic azadiene, reaction with 2-aminopyrroles occurs by substitution by addition-elimination instead of cycloaddition as mentioned in this paper.
11 citations
Journal Article•
TL;DR: The data and brief analysis included are sufficient enough to show that the Slovak system represents a typical example of the potential of performance management and performance financing being significantly limited, if not destroyed.
Abstract: The aim of our paper is a preliminary evaluation of the introduction of performance management and performance financing arrangements in the Slovak higher education system – accreditation and formula based performance financing. This evaluation will be mainly based on the assessment of short-term impacts of the above mentioned instruments and is expected to invite further professional discussion. We feel that the data and brief analysis included are sufficient enough to show that the Slovak system represents a typical example of the potential of performance management and performance financing being significantly limited, if not destroyed. Not only because of improperly defined indicators, which are too much input and quantity orientated, but very much also due to a lack of resources (the ratio of public expenditures for higher education to the GDP in Slovakia is significantly below EU average), as well as the politicization of the system.
7 citations
TL;DR: In this paper, the static longitudinal linear and non-linear optical properties of small trans-transoid polymethineimine oligomers have been obtained at the CCSD(T) level using the 6-311++G(3df,3pd) basis set and MP2-optimized ground state geometries.
Abstract: With the aim to decrease the uncertainties in the so far predicted values, the static longitudinal linear and non-linear optical properties of small trans-transoid polymethineimine oligomers have been obtained at the CCSD(T) level using the 6-311++G(3df,3pd) basis set and MP2-optimized ground state geometries. Our results are compared with previous theoretical data obtained at lower levels of theory and/or using less accurate geometries. In addition, the second hyperpolarizability is reported for the first time. Electron correlation effects are analyzed at various levels of the theory, including MP2, CCSD and CCSD(T). It turns out that (i) CCSD(T) systematically decreases dipole moment values (reduced per unit cell) by 4–5%, (ii) a previously published MP2 extrapolated polymeric dipole polarizability value of 126.1 a.u. should be considered as an upper bound, and (iii) our CCSD(T) results on the first hyperpolarizability lead to a significantly smaller estimation (by about 60%) of the polymeric value.
6 citations
TL;DR: In this article, a category version of the Poincare recurrence theorem for a non-invertible map of a Baire space which is continuous, nearly feebly open and has no nonempty open wandering set was proved.
TL;DR: All prime 3-manifolds of Heegaard genus two described by 6-tuples of complexity at most 21 are described.
TL;DR: In this article, a finite non-boolean bounded distributive lattice was proposed for the class of all natural dualities that are known to be full but not strong at the finite level.
Abstract: The realm of natural dualities that are known to be full but not strong at the finite level is a very small one, consisting of a single example. This example, based on the three-element bounded distributive lattice, was presented by Davey, Haviar and Willard [8]. In this paper, we extend this realm to the class of all natural dualities based on a finite non-boolean bounded distributive lattice.
01 Jan 2007