Daniel Lignon
91 articles published in Tangente
Math for everyoneN°213Aug 28, 2023Perrin's test for prime numbers… well, almost!
The Perrin numbers are named after Raoul Perrin, a French engineer (1841–1910) who served as president of the Société mathématique de France in 1908.
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History and CultureN°213Aug 28, 2023Fibonacci for rabbits
These numbers are named after the 13th-century Italian mathematician Leonardo Fibonacci (c. 1175–c. 1250).
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Math for everyoneN°87Aug 24, 2023Convexity is easy to visualize
Convex geometry took off during the 1960s, particularly because of its applications in probability theory and optimization
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Math for everyoneN°87Aug 24, 2023A brief anthology
Mathematics abounds in inequalities, often drawing on differential or integral calculus. Many problems can be solved with their help. So let's explore them!
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Math for everyoneN°87Aug 24, 2023A little order…
Dictionary words, like points in the plane, can be put in order. Each choice of method—alphabetical order, lexicographic order, and so on—corresponds to an ordering: it is up to each of us to choose the order relation that suits our needs!
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Math for everyoneN°87Aug 23, 2023Solving an inequality
Some of our readers no doubt have unpleasant memories of inequalities.
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Math for everyoneN°87Aug 23, 2023The usual order relation on numbers
Once their values are known, any two numbers can be compared—whether they are integers, fractions, or real numbers—and we can say which is smaller.
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History and CultureN°212Jun 26, 2023Research
Singmaster's conjecture, the Polymath projects, the Green–Tao theorem…
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History and CultureN°212Jun 21, 2023Some results
Terence Tao has successfully tackled many mathematical conjectures. Here are a few examples.
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History and CultureN°210Feb 23, 2023Waring's problem: 250 years of research!
Since the 18th century, a famous problem—Waring's conjecture—has challenged mathematicians. Every integer N is a sum of at most four squares, or of at most nine cubes. Likewise, given an integer n, can every N be expressed as a sum of at most g(n) nth powers, and if so, what is the smallest possible value of g(n)?
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History and CultureN°210Feb 21, 2023The famous number 1729
The smallest integers that can be written as a sum of two cubes in three different ways, then four different ways, and so on, are often called taxicab numbers.
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Math for everyoneN°209Dec 27, 2022Happy New Year! The properties of 2023
As is now customary, the Tangente team explores the properties of the year number in our Gregorian calendar. What can we say about 2023? We will examine it in particular through the Josephus sieve.
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