On tangent geometry and generalised continuum with defects

This paper introduces tools on fibre geometry towards the framework of mechanics of microstructured continuum. The material is modelled by an appropriate bundle for which the associated connection and metric are induced from the Euclidean space by a smooth transformation represented by a fibre morphism from the bundle to Euclidean space. Furthermore, the general kinematic structure of the theory includes macroscopic and microscopic fields in a multiscaled approach, including large transformation. Defects appear in this geometrical point of view by an induced curvature, torsion and non-metricity tensor in the induced geometry. Special attention is given to transport along a finite path in order to extend the standard infinitesimal analysis of torsion and curvature to a macroscopical point of view. Both theoretical and numerical analysis may be handled without additional difficulties. Accordingly, several examples of transformation involving the distribution of material defects are exhibited and analysed.

Intuitionistic/Constructive Accounts of the Continuum Today

In this chapter we describe the properties of the continuum as it is conceived in the intuitionistic and constructive senses. The chapter ends with an account of the continuum as it is conceived in Smooth Infinitesimal Analysis, a recently developed approach to mathematical analysis based on nilpotent infinitesimals.

Introduction

The idea (or, perhaps better, the need) for this volume became clear to us when we were working on our monograph, Varieties of continua: from regions to points and back. 1 We deveoped an interest in various contemporary accounts of continuity: the prevailing Dedekind–Cantor account, smooth infinitesimal analysis (or synthetic differential geometry), and intuitionisic analysis. Each of these theories sanctions some long-standing properties that have been attributed to the continuous, at the expense of other properties so attributed. The intuitionistic theories violate the intermediate value theorem, while the Dedekind–Cantor one gives up the thesis that continua are unified wholes, and cannot be divided cleanly. The slogan is that continua are viscous, or sticky....

MARIA GAETANA AGNESI, ENFANT PRODIGE, MATEMATICA, PIA NOBILDONNA

Maria Gaetana Agnesi (1718-1799) was a prominent figure in eighteenth-century Milan. A child prodigy, and an attraction in the scientific and philosophical disputes organized in the paternal home, she was the first woman to publish a mathematical treatise, the Instituzioni analitiche ad uso della gioventù italiana (1748), a clear and systematic presentation of both Cartesian geometry and infinitesimal analysis. Among the curves studied in that work is the versiera, (witch) the cubic curve that is still associated with her name. Appointed by Pope Benedict XIV in 1750 on the chair of mathematics at the University of Bologna, she did not accept that assignment. After her father’s death in 1752, she left mathematics to devote herself entirely to pious works, and to taking care of poor and infirm women in the Pio Albergo Trivulzio, where she spent the last fifteen years of life.

Некоторые замечания о нестандартных методах анализа. I

This and forthcoming articles discuss two of the most known nonstandard methods of analysis---the Robinsons infinitesimal analysis and the Boolean valued analysis, the history of their origination, common features, differences, applications and prospects. This article contains a review of infinitesimal analysis and the original method of forcing. The presentation is intended for a reader who is familiar only with the most basic concepts of mathematical logic---the language of first-order predicate logic and its interpretations. It is also desirable to have some idea of the formal proofs and the Zermelo--Fraenkel axiomatics of the set theory. In presenting the infinitesimal analysis, special attention is paid to formalizing the sentences of ordinary mathematics in a first-order language for a superstructure. The presentation of the forcing method is preceded by a brief review of C.Godels result on the compatibility of the Axiom of Choice and the Continuum Hypothesis with Zermelo--Fraenkels axiomatics. The forthcoming article is devoted to Boolean valued models and to the Boolean valued analysis, with particular attention to the history of its origination.

Infinitesimals, Nations, and Persons

I compare three sorts of case in which philosophers have argued that we cannot assert the Law of Excluded Middle for statements of identity. Adherents of Smooth Infinitesimal Analysis deny that Excluded Middle holds for statements saying that an infinitesimal is identical with zero. Derek Parfit contended that, in certain sci-fi scenarios, the Law does not hold for some statements of personal identity. He also claimed that it fails for the statement ‘England in 1065 was the same nation as England in 1067’. I argue that none of these cases poses a serious threat to Excluded Middle. My analysis of the last example casts doubt on the principle of the Determinacy of Distinctness. While David Wiggins's ‘conceptualist realism’ provides a metaphysics which can dispense with that principle, it leaves no house-room for infinitesimals.