Daniel Lignon
91 articles published in Tangente
Math for everyoneN°84Nov 21, 2022Envelope of a family of lines
Using tangency, a family of lines can also define a curve.
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Math for everyoneN°84Nov 21, 2022Tangents and derivatives
For many people, tangents and derivatives go hand in hand.
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Math for everyoneN°84Nov 17, 2022Beyond Descartes
Several results in the plane and in space generalize Descartes' theorem on the curvatures of tangent circles.
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History and CultureN°208Oct 24, 2022Yitang Zhang's long, solitary quest
Born in China in 1955, Yitang Zhang developed an interest in mathematics at an early age: at the age of 10, he discovered prime numbers and the puzzle of Fermat's Last Theorem. But during the Cultural Revolution, he was sent to work in the countryside with his mother and was unable to continue his studies.
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Math for everyoneN°208Oct 21, 2022Jobs and the economy: the importance of mathematics
In mid-September, the Institut national des sciences mathématiques et de leurs interactions (INSMI) at the CNRS published a study on the impact of mathematics on the economy and employment.
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Math for everyoneN°208Oct 21, 2022Roger Apéry and the irrationality of zeta(3)
Greek on his father’s side, Roger Apéry (1916–1994) spent his childhood in Lille (Nord) before moving to Paris in 1926. Living conditions there became difficult following the 1929 crisis and his father’s loss of his engineering job. To escape this environment, he placed his faith in France’s state school system and academic success.
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History and CultureN°207Aug 19, 2022Alexandre Grothendieck's method
Alexandre Grothendieck (see our feature in Tangente 162, 2015) left an indelible mark on 20th-century mathematics.
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Math for everyoneN°207Aug 19, 2022Pioneers, past and present
Meet some of the pioneers of abstraction in mathematics.
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Math for everyoneN°206Jun 21, 2022Clockwise
Clock hands turn clockwise, rather than counterclockwise. Why?
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History and CultureN°82May 19, 2022Hilbert's thirteenth problem
At the second Congress of Mathematicians, held in Paris in the summer of 1900, David Hilbert presented a list of research questions that he considered important. The list contains twenty-three problems spanning every field: algebra, geometry and analysis.
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Math for everyoneN°82May 19, 2022Tales of roots
The roots of unity form an abelian group. A quick refresher...
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History and CultureN°82May 18, 2022Before Abel and Galois
Until the end of the 18th century, algebra was essentially about solving algebraic equations. That chapter in the history of algebra closed with the work of Abel and Galois. Before them, what questions occupied mathematicians? What problems could they hope to solve?
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