JEAN LOUIS LEGRAND
29 articles published in Tangente
Math for everyoneN°217Apr 09, 2024Diophantus of Alexandria: an unknown figure
As noted on www.diophante.fr, which has just celebrated its 20th anniversary, the Greek mathematician Diophantus left us some remarkable works on arithmetic. A journey into history will reveal his extraordinary talent.
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Math for everyoneN°213Aug 25, 2023Making counting easier
Counting the elements of certain sets is not always straightforward. In the last century, William Burnside, a mathematician specializing in group theory, established a result that simplifies the calculation of the number of objects in certain finite sets.
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Math for everyoneN°210Feb 23, 2023A "maths special" issue
La Jaune & La Rouge, the monthly magazine of the École polytechnique alumni and graduates association (AX), devotes its February 2023 feature section to mathematics.
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Math for everyoneN°205Apr 20, 2022An epidemic of ODEs
In epidemiology, mathematical modeling has three aims: to understand, describe, and predict. Since the focus is on what happens in the "fairly distant" future, continuous-time models involving differential or partial differential equations are generally preferred.
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Math for everyoneN°202Oct 13, 2021Elegant methods for solving problems (3)
The final installment in our three-part series on methods for solving problems with a minimum of technical machinery. The aim is to discover an imaginative, original approach that shifts the puzzle into familiar territory.
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Math for everyoneN°201Aug 20, 2021Elegant problem-solving methods (2)
The beauty of mathematical problems often lies in an imaginative method—a "haha," as Martin Gardner called it—that makes the solution seem obvious, provided we can find a fresh perspective.
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Math for everyoneN°201Aug 20, 2021Area and barycenter
Barycentric coordinates offer a fresh approach to Routh's theorem and its applications to several results in Euclidean geometry.
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Math for everyoneN°200Jun 11, 2021Elegant problem-solving methods
The appeal of recreational mathematics is that it requires little formal knowledge. Yet there are ingenious techniques that are hardly ever taught.
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Math for everyoneN°78May 19, 2021The builders' geometric constructions
Several centuries before the Renaissance, whether building a church or a fortress, builders needed only a compass and an unmarked straightedge to draw arcs, pointed arches, basket-handle arches and rose windows. Let us explore the basic geometry behind their methods.
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History and CultureN°194May 20, 2020When Conway follows in Einstein's footsteps
John Conway joined forces with Simon Kochen to prove the free will theorem. This result calls for a reassessment of quantum mechanics, without necessarily tying it to probability. It casts new light on a paradox highlighted by Einstein.
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Math for everyoneN°193Mar 23, 2020In logic and combinatorics
In mathematical and logical puzzles, often inspired by observations of everyday life, polynomials can crop up in surprising ways. Geometry, binary logic and algorithms, peg games, combinatorics… no field is immune!
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Math for everyoneNov 25, 2019Divide and conquer
Many arithmetic problems can be solved using standard methods, whether elementary or advanced. But some puzzles call for a basic concept—divisibility—and a little ingenuity.
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