Libro del Mes: Cuentos con Cuentas

CuentosEl libro del mes de octubre es Cuentos con Cuentas, por Miguel de Guzmán (Labor, Barcelona, 1984).

También está publicado en inglés bajo el título The Countingbury Tales, traducido por Jody Doran y publicado por World Scientific (2000).

Echar un vistazo al libro.

Miguel de Guzmán escribió libros similares, el mas conocido es Aventuras Matemáticas, que también está traducido al chino, finlandés, francés y portugués.

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A revanche dos infinitesimais

A autora original é Michèle Artigue. Traduzido por Pedro Malagutti (UFSCar, Brasil) e Cydara Cavedon Ripoll (UFRGS, Brasil).

Os infinitesimais desempenharam um papel essencial no surgimento e desenvolvimento do cálculo diferencial e integral. O ganho evidente com esse cálculo não impediu, contudo, recorrentes debates sobre a natureza de tais objetos e a legitimidade de seu uso. Ao final do século XIX, quando a construção dos números reais a partir dos inteiros e a definição moderna da noção de limite forneceram as fundações sólidas ao cálculo diferencial e integral, os infinitesimais e a metafísica que os cerca foram rechaçados, e o seu uso passou a ser percebido como sinônimo de práticas pouco rigorosas e doravante então encerradas. No entanto, a linguagem dos infinitesimais continuou sendo utilizada, por exemplo, na física e, mesmo na matemática, ela nunca desapareceu completamente do discurso informal e do pensamento heurístico de muitos pesquisadores.

Afinal, é esta linguagem realmente incompatível com o rigor matemático? E o que ela oferece de interessante, de específico que explica sua permanência?

A análise não standard desenvolvida no século XX permitiu responder estas questões, e, aos infinitesimais, permitiu terem a sua revanche.

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Mathematics Today

MathToday2_13cover
October’s site of the month: Mathematics Today

Mathematics Today is a magazine published by the UK Institute of Mathematics and its Applications.

It is a general interest magazine about mathematics intended for those interested in the subject (by christopher). Much material is UK-specific, however it contains many general articles that are downloadable from the website.

 

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Cuentos Con Cuentas

CuentosOctober’s Book of the Month is Cuentos Con Cuentas by Miguel de Guzman (Labor, Barcelona, 1984).

This is also published in English under the title The Countingbury Tales, translated by Jody Doran and published by World Scientific (2000).

Have a look inside.

Miguel de Guzman wrote other similar books, the most well known being Aventuras Matematicas which is also published in Chinese, Finnish, French and Portuguese.

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Trying to predict a floating leaf: chaos and predictions

Jahreszeit__Herbst__Blatt__Baum__rot__farbig__Wasser__schwimmenOriginating author is César R. de Oliveira, Universidade Federal de São Carlos.

What path will a leaf follow floating down a turbulent stream? Is it even possible to make a mathematical model that will predict such motion? Is this the same sort of problem as predicting the path of planets as they move round the sun? Even when we know all the rules governing the motion of an object, and can determine precisely the initial conditions, it turns out that some motions can be predicted and some cannot. And it is not just a matter of complexity: we can model unpredictable systems with very simple equations. In this Vignette we illustrate mathematically the existence of chaotic dynamical systems using the decimal form of real numbers. You will see how the unpredictability can be simply generated. One of the main goals of theoretical models is to make (good) predictions. However, there are deterministic dynamical systems that in practice are unpredictable; they are the so-called chaotic systems. The aim of this text is to discuss how this unpredictability is generated, and the main tool here will be the decimal representation of real numbers.

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الأبعاد العليا

الأبعاد العليا

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How to get rid of quantifiers?

Quantifiers_5Originating authors are Reinhard Oldenburg and Michele Artigue.

How do computer packages do abstract algebraic problems such as proving statements “for all x” or finding whether a Real Number x with certain conditions exists?

Recent advances draw on theorems in mathematical logic, as well as improvements in computing.

High school students learn how to solve problems such as the following: « For what values of the real number c, does the polynomial P(x)=x^2+cx+c have two distinct real roots ? », and algorithmically get the answer: c<0 or c>4. Doing so, they have in some sense, found a way of transforming the sentence expressing the problem (\exists x_1 \, \exists x_2 \, (x_1\not= x_2 and P(x_1)=0 and P(x_2)=0) involving the two existential quantifiers ‘there exists x_1’ and ‘there exists x_2’ into the sentence c<0 or c>4 which no longer includes quantifiers. For what kind of problems is this possible, theoretically but also practically with an effective computer program? In 1938, thanks to a theorem of elimination of quantifiers proved by the logician Alfred Tarski, a decisive step was achieved regarding these questions, but this was not at all the end of the story… READ MORE

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Bridges

Bridges Org

Septembers Seite des Monats ist: Bridges

Bridges ist eine Organisation, die die jährliche Bridges Konferenz über Mathematik und Kunst leitet. Die Seite beinhaltet viele Bilder und Quellen verschiedenster künstlerischer Darstellungen: von Poesie bis zu Modellen, von Tanz bis zu Origami, von Jonglieren bis zur Malerei. Der Reiter -Resources- auf der Homepage enthält Links zu anderen Seiten, die für Lehrer von Interesse sind.

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Mathematical Models

Mathematical Models

September’s featured book of the month is “Mathematical Models” by H.M. Cundy and A.P. Rolett.

This classic was first published in 1952 by Oxford University Press, but was republished in paperback by Tarquin in 1981.

As well as nets polyhedra, it has a wide variety of linkages and dissections, as well as several mechanical models.

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Mathematical Models

Mathematical Models

September’s featured book of the month is “Mathematical Models” by H.M. Cundy and A.P. Rolett.

This classic was first published in 1952 by Oxford University Press, but was republished in paperback by Tarquin in 1981.

As well as nets polyhedra, it has a wide variety of linkages and dissections, as well as several mechanical models.

Posted in Book of the Month | Leave a comment