DANIEL JUSTENS
90 articles published in Tangente
History and CultureN°62Feb 15, 2017The saga of economic indicators 1
What do these economic indicators we hear so much about in the media actually mean?
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Math for everyoneN°62Feb 15, 2017Inventory management in a stochastic setting
From small bakeries to hypermarkets, retailers face dilemmas with every product they sell. How much should they make available to customers? Too little, at the risk of losing sales, or too much, at the risk of being left with unsold goods? And, of course, at what price? A probabilistic model can help them decide.
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Math for everyoneN°62Feb 14, 2017Money and inflation: two inseparable concepts
The desire for wealth fuels many people's ambitions and sometimes dictates their behavior. While no one now doubts the usefulness of money in our modern way of life (!), who knows its history? And how is money linked to inflation?
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Math for everyoneN°174Jan 17, 2017Other optimizations
Optimization techniques are sometimes hidden in other subjects. Here are a few examples
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Math for everyoneN°174Jan 16, 2017An insidious effect: meta-comprehension
How do mathematicians choose names for new concepts? They draw inspiration from the world around them and from the mental images these new objects evoke. In the process, everyday words take on new meanings, sometimes causing confusion...
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Math for everyoneN°173Nov 21, 2016Deduction or induction... What about abduction?
A host of tiny clues leads the detective Sherlock Holmes to formulate a theory, moving from the particular to the general. He is well aware that his method leads to the truth only if it is confirmed by the facts—that is, by observation!
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Math for everyoneN°61Oct 07, 2016What exactly are axioms?
In mathematics, every proof starts from premises assumed to be true. What particular form must these premises take to become axioms, the foundation of all our current theories?
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Math for everyoneN°61Oct 07, 2016Constructing numbers: a long history
In the beginning was number... If we go back to the very origins, these objects were represented by pebbles before being encoded by symbols. In fact, there are numbers to suit every taste! As everyone knows, when you love something, you don't count the cost...
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Math for everyoneN°61Oct 05, 2016From a collection of objects to a set
A set can be defined extensionally or intensionally. Constructing the natural numbers then becomes an easy but instructive exercise. Yet beware the apparent simplicity of a set viewed as a mere collection of objects: paradoxes lurk...
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Math for everyoneN°171Jul 07, 2016From Brel to Navier–Stokes
Beyond the poetry and the images evoked in Jacques Brel's songs lies a surprising mathematical reality: the basic models used to describe the movement of waves and dunes are identical! Moreover, they are far from having revealed all their secrets.
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Math for everyoneN°170May 17, 2016Solving equations: Rolle's theorem to the rescue
The mean value theorem guarantees that very concrete compounding problems do indeed have a solution, and that applying the standard governing equations does indeed lead to that solution. A dream for any economist!
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Math for everyoneN°169Mar 22, 2016Mathematical semantics and astrological semantics
Horoscope advice can seem sensible. Why is that? While advice in objective areas consists solely of tautologies, subjective advice draws on a multiplicity of meanings, allowing clients always to interpret it as they wish.
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