Husserl on Geometry and Spatial Representation

Husserl left many unpublished drafts explaining (or trying to) his views on spatial representation and geometry, such as, particularly, those collected in the second part of Studien zur Arithmetik und Geometrie (Hua XXI), but no completely articulate work on the subject. In this paper, I put forward an interpretation of what those views might have been. Husserl, I claim, distinguished among different conceptions of space, the space of perception (constituted from sensorial data by intentionally motivated psychic functions), that of physical geometry (or idealized perceptual space), the space of the mathematical science of physical nature (in which science, not only raw perception has a word) and the abstract spaces of mathematics (free creations of the mathematical mind), each of them with its peculiar geometrical structure. Perceptual space is proto-Euclidean and the space of physical geometry Euclidean, but mathematical physics, Husserl allowed, may find it convenient to represent physical space with a non-Euclidean structure. Mathematical spaces, on their turn, can be endowed, he thinks, with any geometry mathematicians may find interesting. Many other related questions are addressed here, in particular those concerning the a priori or a posteriori character of the many geometric features of perceptual space (bearing in mind that there are at least two different notions of a priori in Husserl, which we may call the conceptual and the transcendental a priori). I conclude with an overview of Weyl's ideas on the matter, since his philosophical conceptions are often traceable back to his former master, Husserl.

Compositional analysis for an unbiased measure of soil aggregation

Soil aggregation is an index of soil structure measured by mean weight diameter (MWD) or scaling factors often interpreted as fragmentation fractal dimensions (D-f). However, the MWD provides a biased estimate of soil aggregation due to spurious correlations among aggregate-size fractions and scale-dependency. The scale-invariant D-f is based on weak assumptions to allow particle counts and sensitive to the selection of the fractal domain, and may frequently exceed a value of 3, implying that D-f is a biased estimate of aggregation. Aggregation indices based on mass may be computed without bias using compositional analysis techniques. Our objective was to elaborate compositional indices of soil aggregation and to compare them to MWD and D-f using a published dataset describing the effect of 7 cropping systems on aggregation. Six aggregate-size fractions were arranged into a sequence of D-1 balances of building blocks that portray the process of soil aggregation. Isometric log-ratios (ilrs) are scale-invariant and orthogonal log contrasts or balances that possess the Euclidean geometry necessary to compute a distance between any two aggregation states, known as the Aitchison distance (A(x,y)). Close correlations (r>0.98) were observed between MWD, D-f, and the ilr when contrasting large and small aggregate sizes. Several unbiased embedded ilrs can characterize the heterogeneous nature of soil aggregates and be related to soil properties or functions. Soil bulk density and penetrater resistance were closely related to A(x,y) with reference to bare fallow. The A(x,y) is easy to implement as unbiased index of soil aggregation using standard sieving methods and may allow comparisons between studies. (C) 2012 Elsevier B.V. All rights reserved.

Modelagem inicial para o ensino de geometria eucliadiana plana segundo a teoria da atividade de estudo

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Um estudo de fractais geométricos através de caleidoscópios e softwares de geometria dinâmica

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A produção matemática em um ambiente virtual de aprendizagem: o caso da geometria euclidiana espacial

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

O problema isoperimétrico e aplicações para o ensino médio

Pós-graduação em Matemática em Rede Nacional - IBILCE

Um novo conceito de distância: a distância do táxi e aplicações

Pós-graduação em Matemática em Rede Nacional - IBILCE

Sobre problemas de máximo e mínimo na Geometria Euclidiana

Pós-graduação em Matemática em Rede Nacional - IBILCE

O processo ensino-aprendizagem-avaliação de geometria através da resolução de problemas: perspectivas didático-matemáticas na formação inicial de professores de matemática

Pós-graduação em Educação Matemática - IGCE

Estudando geometria através de dobraduras

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Investigações sobre sistemas axiomáticos na geometria euclidiana

Pós-graduação em Educação Matemática - IGCE

Área e volume: a transição da noção de medida à de área e de volume

Pós-graduação em Matemática em Rede Nacional - IBILCE

Proposições geométricas com animações

Pós-graduação em Matemática em Rede Nacional - IBILCE

Sobre pavimentações do plano euclidiano

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Construções euclidianas e o desfecho de problemas famosos da geometria

Construction techniques with ruler and the compasses, fundamental on Euclidean geometry, have been related to modern algebraic theories such as solving equations and extension of bodies from the works by Paolo Ruffini (1765-1822), Niels Henrik Abel (1802-1829) and Evariste Galois (1811-1832). This relation could provide an answer to some famous problems, from ancient Greece, such as doubling the cube, the trisection Angle, the Quadrature of the Circle and the construction of regular polygons, which remained unsolved for over two thousand years. Also important for our purposes are the notions of algebraic numbers, transcendental and the criteria for constructability, of those numbers. The objective of this study is to reconstruct relevant steps of geometric constructions with ruler (unmarked) and the compasses, from the elementary to the outcome buildings, in the nineteenth century, considering those mentioned problems.