Let $Q={\left(Q_k\right)}_{k\ge 0},Q_0=1,Q_{k+1}=q_k{Q}_k,q_k\ge 2$, be a Cantor scale, ${𝐙}_Q$ the compact projective limit group of the groups $𝐙/Q_k𝐙$, identified to ${\prod }_{0\le j\le k-1}𝐙/q_j𝐙$, and let $\mu$ be its normalized Haar measure. To an element $x=\{a_0,a_1,a_2,\cdots \},0\le a_k\le q_{k+1}-1$, of ${𝐙}_Q$ we associate the sequence of integral valued random variables $x_k={\sum }_{0\le j\le k}{a}_j{Q}_j$. The main result of this article is that, given a complex $𝐐$-multiplicative function $g$ of modulus $1$, we have$$\underset{x_k\to x}{lim}(\frac{1}{x_k}\sum _{n\le x_k-1}g\left(n\right)-\prod _{0\le j\le k}\frac{1}{q_j}\sum _{0\le a\le q_j}g\left(a{Q}_j\right))=0\mu \text{-a.e}.$$

For infinite discrete additive semigroups $X\subset [0,\infty )$ we study normed algebras of arithmetic functions $g:X\to ℂ$ endowed with the linear operations and the convolution. In particular, we investigate the problem of scaling the mean deviation of related multiplicative functions for $X=log\mathbb{N}$. This involves an extension of Banach algebras of arithmetic functions by introducing weight functions and proving a weighted inversion theorem of Wiener type in the frame of Gelfand’s theory of commutative Banach algebras.

Si $p_k$ est le k${}^{ème}$ nombre premier, $\theta \left(p_k\right)={\sum }_{i=1}^{k}log{p}_i$ la fonction de Chebyshev. Nous obtenons de nouvelles estimations et des améliorations des bornes données par Rosser et Schoenfeld, Schoenfeld et Robin pour les fonctions$$p_k,\theta \left(p_k\right),S_k=\sum _{i=1}^k{p}_i,\text{et}S\left(x\right)=\sum _{p\le x}p.$$Ces estimations sont obtenues en utilisant des méthodes basées sur l’intégrale de Stieltjes et par calcul direct pour les petites valeurs.