Search

Some years ago the authors of the present paper found in the Fondo Padoa lying in the Mathematical Library of Genoa University a manuscript of 11 pages by Alessandro Padoa with the title A proposito di un nuovo sistema fondamentale della geometria elementare. It seems to be ready for publication and contains also typographical instruction for printing. Other investigations on Padoa and his rôle in Peano's school led in a series of recent papers to a probably complete list of Padoa's publications where, however, the above mentioned manuscript is not present and, therefore, is likely to be considered an unpublished paper. It's a matter of fact that the whole of Padoa's scientific production has to be integrated by some works that he didn't publish. The unpublished paper under examination deals with the axiomatization of elementary geometry given by Mario Pieri in 1899 in "Della geometria elementare come sistema ipotetico deduttivo. Monografia del punto e del moto", where, as it is well-known, elementary geometry is based on the primitive notions of point and movement and on 20 postulates. Padoa agrees with Pieri's proposal to define segment starting from point and movement; he suggests, however, some modification to the original set of postulates and gives a (partial) proof of their independence. The unpublished paper reveals the interest of Padoa in this subject-matter and, in some sense, his idea of participating in the already consolidated field of research represented by Pieri's results. [ABSTRACT FROM AUTHOR]

Copyright of Calcolo is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The article discusses the presence of matter (organic as well as inorganic) in twentieth-century Italian poetry. The paper offers a diachronic survey of some exemplary authors and texts (Marinetti, Gozzano, Montale, Giudici, Caproni, and Sereni), highlighting the different utilisations of objects and things within literary texts. Objects and things define spaces and places in subjects' lives, support their identity, and document various ages and generations. The death of their owners makes things and objects lose their original purpose and find different functions with new subjects. In this context, they appear as miniature eternities always ready for a connection with new subjects. [ABSTRACT FROM AUTHOR]

Copyright of Atti della Accademia Nazionale dei Lincei. Rendiconti Lincei: Scienze Fisiche e Naturali is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Il Nuovo Cimento: C is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atti della Accademia Nazionale dei Lincei. Rendiconti Lincei: Scienze Fisiche e Naturali is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atti della Accademia Nazionale dei Lincei. Rendiconti Lincei: Scienze Fisiche e Naturali is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Atti della Accademia Nazionale dei Lincei. Rendiconti Lincei: Scienze Fisiche e Naturali is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In this paper the existence of infinitely many eigenvalues for the non linear boundary value problem Ωt R bounded and $$\bar \lambda \in $$ (λ, λ) where λ and λ are the first and the second eigenvalue of - Δ respectively. The eigenvalues are characterized by the critical levels of a suitable functional on a smooth unbounded manifold. The usual method is not applicable because the functional is not positive definite and the Palais-Smale condition is not satisfied. We applies a technique introduced in a preceding paper [3]. [ABSTRACT FROM AUTHOR]

This paper is concerned with boundary value problems for linear partial differential equations of elliptic type in a plane sector; in the first part of the paper Sobolev weight spaces have been studied and embedding and trace theorems have been proved; in the second part it is proved that problem is index type. [ABSTRACT FROM AUTHOR]

It is known that the correct formulation of rational thermodynamics for mixtures requires an inequality more general than the Clausius-Duhem principle. On the other hand, in a recent paper on the thermodynamics of 'interstitial working'[2] it was pointed out the need to correct the classical balance law of internal energy. There is no good reason for modifying both, however. It is worth to derive, hence, the most general expression of the Second Law by keeping the First in its classical form, as shown in a previous paper [4], or, what is the object of this article, to look for the most general formulation of the First Law assuming the Clausius-Duhem inequality as the Second. As a consequence of results obtained here, the statement of the First Principle needs not to be changed in the class of 'simple material'. Thus, it is worth noting that a generalized expression of the First Law applies only non-simple materials, like as Korteweg fluids. [ABSTRACT FROM AUTHOR]

The first part of this paper studies the stability and the order of a numerical method for the integration of the second kind of Volterra equations. This method is obtained by differentiating m-times ( m>-2) the Volterra equation and by integrating the «differential equations system» obtained via the trapezoidal rule. The proposed method has second order and an absolute stability region equal to the third quadrant of the plane ( hλ, h μ). The second part of this paper, analyzes the stability properties and also the order of a class of numerical methods, obtained via the integration of the previous «differential equations system» though backward differentiation. It is shown that these methods have a high order and a very large stability region. [ABSTRACT FROM AUTHOR]

Selection of a technical vocabulary, thesaurus construction and document indexing are critical phases in the organization of Information Retrieval Systems. This paper presents a methodology for the selection of terms to be inserted in a technical vocabulary. After a morphological analysis of texts, a statistical analysis is performed, based on a new method to identify a meaningful interval on the Zipf's frequency distribution of terms. An experiment on a collection consicting of some 5000 abstracts of papers on isotope separation indicates that this method is very promising for automatic selection of technical vocabularies. [ABSTRACT FROM AUTHOR]

This paper is intended to show that an algebraic approach can give useful suggestions to design efficient algorithms solving combinatorial problems. The problems we discusses in the paper are: [ABSTRACT FROM AUTHOR]

Copyright of Calcolo is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Calcolo is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Calcolo is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the first two sections of this paper existence theorems are proved for optimal control problems described either by Fredholm systems of integral equations (with control appearing nonlinearly) on a given (possibly infinite) measure space, eventually in presence of eigenvalues, or by Urysohn systems, both with pointwise and integral constraints on controls and states. Controllability is assumed throughout the paper. In the last section necessary conditions are proved for optimal controls of Fredholm systems (a minimum principle in pointwise, or « differential » form), and theorems (that seem to be new also for the corresponding ordinary differential control systems) are deduced about bang-bang and regularization properties of the optimal control (s) (which turns out to be a continuous function except for a finite number of points, if positivity and semicontinuity assumptions hold about the data): in some particular cases the optimal control will be piecewise constant. All these results are independent on the known ones. [ABSTRACT FROM AUTHOR]

Copyright of Annali di Matematica Pura ed Applicata is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Pure & Applied Geophysics is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This paper contains the doscription of a method of computation of the power spectrum of a stochastic signal that minimizes the error intrinsic with the direct way of computation. The method is a generalization of the mean value rejection and prewhitening techniques. It grounds itself on the adaptive construction of a filter which transforms the true spectrum in a white one by means of the linear filtering of the signal given, whichever the true spectrum may be. The method is suitable of automatic computation in digital form. Various examples of the results obtained by means of a Fortran IV program, also given in the paper, are furnished and discussed. [ABSTRACT FROM AUTHOR]

In a previous paper the numerical solution of a particular boundary-value problem for the «weakly linear» equation was obtained and the convergence of a suitable finite-difference scheme was proved. This paper is concerned with the more general equation where; the solution is obtained using the same finite-difference scheme as in the previous paper, and sufficient condition for its convergence are given for this new case [ABSTRACT FROM AUTHOR]

This paper deals with the language PREFOR, an extention of FORTRAN IV which allows to represent with single identifiers sets of data widely arbitrary and of variable length, The language allows to act upon the sets and upon FORTRAN variables by means of programme defined operators. The declarations of the new operands and operators are added to FORTRAN statements as well as executable statements, describing the calculations upon such elements and FORTRAN expressions, and other organizing statements concerning the dynamic storage assignement required by the variable length operands. Furthermore, referring to the characteristics of dynamic storage organization upon which the language is based, the paper shows the rules for the translation of a PREFOR programme into a FORTRAN programme which can be compiled and executed as usual. Finally a programme is described which can perform this translation upon the IBM 7040 and 7090 and the UNIVAC 1108 processors. [ABSTRACT FROM AUTHOR]

Copyright of Calcolo is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Some authors have proved that a minimal two-level NAND or NOR network can be obtained by the convetional procedures for determining minimal normal forms. But when either the complements of some input variables are not available or the gates have a limited number of inputs, the two-level synthesis is generally impossible; and no procedure has been described for the minimal sunthesis of networks having more than two levels of gates. In this paper some new procedures are described for the synthesis of NAND or NOR networks having more than two levels of gates. In the first sections the properties are briefly described, by which a NAND or NOR expression is equivalent to a conventional expression containing only the AND and OR operators; also, the problem of determining a minimal two-level NAND or NOR network is summarized. Then the synthesis of three-level NAND or NOR networks is considered, in case that both the true and complemented values of input variables are available, and the gates can have an unlimited number of inputs (condition 1). A new procedure is described which makes it possible to find one of the minimal NAND or NOR networks, having a tree-shaped structure, and which gives also quasi-minimal solutions for the general case in which the output of a gate can be connected to the inputs of more than one gate of the next level. The procedure derives from the methods described in a preceding paper by the present author for determining the minimal «sums of products of sums» of an assigned function; but some properties and the particular definition of cost make it possible to apply a computation technique, which simplifies this problem considerably. Then the synthesis problem is considered when the gates can have an unlimited number of inputs but the complements of some of the input variables are not available (condition 2). In this case the two-level synthesis is generally impossible (a simple necessary and sufficient condition for a two-level solution to exist is proved); on the contrary, a three-level NAND or NOR network always exists, which implements the assigned function. This network can be determined with the procedure which has been described for determining the minimal three-level networks in condition 1, but the new conditions simplify the problem and a remarkable reduction of the computation work is possible. Lastly the following cases are considered: In these cases a two- or a three-level synthesis may be impossible, but one can always verify whether a two- or a three-level network implementing the assigned function exists. However a simple procedure is described, which always makes it possible to find a quasi-minimal solution characterized by more than three levels of gates. [ABSTRACT FROM AUTHOR]

Copyright of Epistemologia is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Epistemologia is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Epistemologia is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Neohelicon is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Why are there so few women in philosophy? Do women dislikes rigorous argumentation? Recently, Wesley Buckwalter e Stephen Stich have argued that women and men tend to have different philosophical intuitions and that these differences might play a role in explaining the underrepresentation of women in philosophy. To the contrary, in this paper, I defend the view that intuitions are in part socially constructed and product of stereotypical behaviours. The paper is divided in two parts. In the first, I present Buckwalter and Stich's view as characterized by the two following theses: (i) there are significant differences between men and women in intuitive responses to some philosophically important thought experiments; (ii) women intuitions do not accord with those of professional philosophers insist are correct. In my analysis, particular attention is given on their hypothesis about the gender gap in academia as, in part, the result of a selection effect: women, because of the fact they do not have standard intuitions, become convinced they are not good in philosophy or are discouraged from continuing in philosophy. In the second part of the paper, I show why Buckwalter and Stich's approach is inadequate, by showing that the data in the works they reported are too low to support their conclusion (i.e. in many important thought experiments are no significant gender differences) and their thesis does not match with the idea the intelligence is not a fixed entity and the view that gender as social construction differs from one society to another. Gender differences in responses to thought experiments, I conclude, are not differences in intuitions per se, but in how women and men interpret the cases at issue, and are not an important part of the explanation for the gender gap in philosophy. [ABSTRACT FROM AUTHOR]

Alessandro Padoa was born on October 14, 1868, in Venice and died on October 25, 1937, in Genoa. He was a mathematician of the so-called Peano's school and is well-known to logicians mainly for his investigations on the independence, understood as mutual undefinability, of primitive concepts of an axiomatic theory. In this framework he formulated in 1900 (at the International Congress of Philosophy in Paris) a technique, to be later known as "Padoa's method", to prove the independence of primitive concepts. In spite of his involvement in the world of research, the main job of Padoa was teaching mathematics in the secondary schools (and this is also the case for many other members of Peano's school). In 1932, however, he got the university teaching degree ("libera docenza") in mathematical logic and in the following years he delivered courses of mathematical logic at the University of Genoa. This paper aims to sketch a short biography of Padoa and to give a list of his publications (more than hundred items, mainly devoted to mathematical logic or to elementary mathematics). In a more general sense the paper deals with some historical data on mathematical logic in Italy in that period and could contribute to a deeper understanding of the role played by Peano's school and of the reasons of its decline. [ABSTRACT FROM AUTHOR]

This paper is the sequel of "Quantificatori generalizzati e logica del primo ordine - I". In that paper I argued that from the point of view of Generalized Quantifier theory one can single out some classes of quantifiers that cannot be identified by first order logic. The discovery of these classes is important because it allows to explain some regularities observed in natural language: in some contexts, only the quantifiers of one of these classes may appear. In this paper I examine existential and partitive contexts in particular. Existential contexts are those in which a NP follows the expression "there is/are...". I show that only one of the three types of quantifiers singled out in the first part of this work is allowed in these contexts, while the other two are not. I try to explain why this happens on the basis of the characterization of those classes I gave in the first paper. Partitive contexts are those of the type "NP1 of NP2". Only the NPs determined by one of identified classes of quantifiers are allowed in NP2 position. Again I try to explain why. [ABSTRACT FROM AUTHOR]

Let G be a group and ϕ an automorphism of G. Two elements x, y ∈ G are called ϕ-conjugate if there exists g ∈ G such that x= g −1 yg θ. It is easily verified that the ϕ-conjugation is an equivalence relation; the number R(ϕ) of ϕ-classes of G is called the Reidemeister number of the automorphism ϕ. In this paper we prove that if a polycyclic groups G admits an automorphism ϕ of order n such that R(ϕ)<∞, then G contains a subgroup of finite index with derived length at most 2 n−1 . [ABSTRACT FROM AUTHOR]

This is the first of a couple of papers in which the problematic relation between quantum ontology and spatio-temporal representation and experience is analyzed. The first paper deals with the deep implications that the discovery of the quantum of action (Planck 1900) and the consequent formulation of quantum theory had on the notion of physical process and the relation part-whole. These implications amount to an ontological degradation of the concept of physical object when processes involving few quanta of action are taken into account. The ontological degradation of the object follows directly from the atomization of processes and entails a dramatic empirical falsification of the worldview of historical atomism (which I call in this paper the spatio-temporal atomism of things). On the other hand, historically, an ontological correlation between the notions of object and process, on the one hand, and those of space and time, on the other, has always been present. Every time there has been a change in the conception of "thing", it has been accompanied, sooner or later, by a corresponding change in the conception of space and time, or vice versa. However, after more than a century since the discovery of process atomization, the ontological degradation of the concept of micro-object does not appear to have affected explicitly the conceptions of space and time. The thesis of the necessity of a deep restructuring of these notions for the solution of the open problems of quantum theory as well as for the synthesis of this theory with general relativity will be defended in the second paper. [ABSTRACT FROM AUTHOR]

An automorphism ϕ of a group G is said to be uniform il for every g ∈ G there exists an h ∈ G such that G= h −1 h ρ . It is a well-known fact that if G is finite, an automorphism of G is uniform if and only if it is fixed-point-free. In [7] Zappa proved that if a polycyclic group G admits an uniform automorphism of prime order p then G is a finite (nilpotent) p′-group. In this paper we continue Zappa’s work considering uniform automorphism of order pg ( p and q distinct prime numbers). In particular we prove that there exists a constant μ (depending only on p and q) such that every torsion-free polycyclic group G admitting an uniform automorphism of order pq is nilpotent of class at most μ. As a consequence we prove that if a polycyclic group G admits an uniform automorphism of order pq then Z μ ( G) has finite index in G. [ABSTRACT FROM AUTHOR]

The process and the entity concepts in chemistry and in physics (with a few words to the same concepts in biology) have been analysed. A first aspect underlined in this paper is the relativity of these two concepts and their relations to the time-scales and to the measurement devises. In mechanics "an object in transformation" can be studied by the help of a differentiation between the "system variables", that they identify the system, and "configuration (or state) variables", that they describe the dynamical state of the system. Instead, in chemistry an entity is an object with characteristic properties (static and dynamical) so particular than it has a proper name. There are entities in both the macroscopic (chemical substances) and the microscopic world (molecules and atoms). A fundamental point underlined in the paper is that in the chemistry picture they exist million of these different objects. It is this complex world the material of the chemical explication of both inanimate and animate things. Also the process concept is different in chemistry and in physics. In the paper we analyse the different interpretation of the substance transformation (reactivity) in these two disciplines: in physics this is considered a modification of the equilibrium condition of a system, due to a perturbation; in chemistry a modification of the system, due to the "death" and the "birth" of different substances. The couple transformation/ transition can identify the point of view of the physics and the chemistry about the substance modification. An important point underlined in the paper is that in the conceptual movement from the physics to the chemistry (and, finally, to the biology) the importance of the entity concept increases and that of the process concept decreases. The entity and process concepts generate in physics and in chemistry two different explanations: the first based on the law and the second on the presence in the system of individual entity and on their properties. In the paper we underline that this implies two different approaches to the material world: that of the physics and that of the chemistry. Two general consequences are shown in the paper: the first about the relation between the chemistry and the physics and the second on the reductionism and about the inanimate-animate and animal-man dichotomies. [ABSTRACT FROM AUTHOR]

A well known result on finite linear spaces due to de Bruijn and Erdös states that the number b of lines is greater than or equal to the number v of points, with b=v if and only if the linear space is either a near pencil, or a projective plane. The problem of characterizing finite linear spaces with small deficiencies s=b−v has been investigated by several authors, especially by Bridges for b=v+1 and de Witte for b=v+2. In this paper we give a unified and short proof for the above mentioned classical results. [ABSTRACT FROM AUTHOR]

Every finite generalized André plane is associated with a spread F′ of the projective space PG(2 t+1, q), which is obtained from a regular pread F replacing in a switching set U some of the subspaces of F. The construction of U is realized by an opportune set A of non-identical automorphisms of the field GF(q t+1). In this paper we characterize the irreducible components of U, when U is obtained by a set A consisting of two automorphisms. In the second paragraph we prove that such switching sets are only of two types. In the third paragraph we provide a constructive rule which is a necessary and sufficient condition for the existence of both the types. In such a way we describe the structure of the spread F′ associated with any finite generalized André plane such that | A|=2. [ABSTRACT FROM AUTHOR]

A buffon problem is studied for a “thin lens” in the plane, a convex test body made by the union of two circular segments both less than or equal to a semicircle. The case in which the lens is “small” compared with the distance between the parallel lines of the Buffon lattice has been treated in [4]. The instance investigated in this paper is the one of a “large” lens, i.e. of a lens which can have multiple intersections with the Buffon lattice. [ABSTRACT FROM AUTHOR]

Copyright of Decisions in Economics & Finance is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)