Signatures des permutations et des mots extraits. (Signatures of permutations and extracted words) (Q1093634)

Any finite injective word of n letters written with a totally ordered alphabet (in particular any permutation) has a specific ``signature'' characterized by the n-1 successive increases \((+)\) or decreases (-). The main result of the paper is that the number of permutations of given signature from which a given word w can be extracted depends only on the signature of w; a method generalizing Viennot's algorithm is given for the calculation of this number.