The reason why, as we saw last week, a magazine whose name I don't want to remember gave “Four” as an absurd answer to the question “How many letters are there in the correct answer to this question?”
It is, in all probability, that they translated it from English, a language in which
four
is the only number whose name has the number of letters indicated by the number itself (although in German it is also four:
vier
).
In Italian, the answer to the question is
tre
, and in Japanese there are two possibilities:
ni
and
san
.
The interesting problem of finding out how many ways seven elements can be grouped into seven groups of three elements, if they have to appear in the same number of groups and two to two only in one group, has not yet been solved by my astute readers. , so it remains pending.
And neither is that of the schoolgirls who walk three by three;
but it is a classic problem and there is abundant documentation about it on the Internet (it even has its own entry on Wikipedia), and I refer those who wish to know the solution to it.
More information
Combinatorics and self-reference
The singular (and plural) sestina
In line with the combinatorial problems addressed in recent weeks, Francisco Montesinos comments: “Given a certain permutation of 7 elements, for example of the 7 colors of the rainbow, how many other permutations will there be such that none of the 7 elements in Does any of them coincide in position with the one it occupies in the given permutation?
A question that invites us to think about the sestina, a peculiar poetic composition in which poetry and mathematics come together.
To compose a sestina, we start with a stanza of six hendecasyllabic verses that do not rhyme with each other, and the final six words of the verses are repeated in five other stanzas of six lines, but always occupying different places: in the second stanza, the ending of the last verse of the first stanza moves to first place, so the first ending becomes the second;
the penultimate moves to third place, so the second becomes the fourth;
the penultimate moves to fifth place and the third becomes sixth.
The first sestinas were composed in the 12th century by the Occitan troubadour Arnaut Daniel (admired by Dante, who called him
il miglior fabbro
del parlar maternal
), and over the centuries it has been chosen and praised by poets of the first magnitude, since Petrarch. to Ezra Pound.
The Catalan poet and plastic artist Joan Brossa is, surely, the contemporary author who has most assiduously cultivated it, since he dedicated four volumes to it and explored possible variants of the classical structure.
As an example of this unique poetic composition, here are the first two stanzas of a sestina by Fernando de Herrera:
To the beautiful glow of your eyes
my chest burned Love in sweet flame
and unleashed the rigor of cold snow,
that hindered the game of my soul,
and in the tight ties of gold and thread
I felt my neck imprisoned and subject to the yoke.
My haughty presumption fell from my neck,
and my eyes saw their loss in you,
after you surrendered your strands to me,
after I burned, lady, in a tender flame;
but happy in its evil lives my soul,
and does not fear the force of the snow.
If the first stanza is ABCDEF and the second FAEBDC, what will the next four be like?
And how is a sestina similar to a sudoku?
To make your task easier, here is a graph that represents the passage from the first stanza to the second:
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