Abstract:
We construct simultaneous rational approximations to the $q$-series $L_1(x_1;q)$ and $L_1(x_2;q)$, and,
if $x=x_1=x_2$, to the series $L_1(x;q)$ and $L_2(x;q)$, where
\begin{gather*}
L_1(x;q)=\sum_{n=1}^\infty\frac{(xq)^n}{1-q^n}=\sum_{n=1}^\infty\frac{xq^n}{1-xq^n},
\\
L_2(x;q)=\sum_{n=1}^\infty\frac{n(xq)^n}{1-q^n}=\sum_{n=1}^\infty\frac{xq^n}{(1-xq^n)^2}.
\end{gather*}
Applying the construction, we obtain quantitative linear independence over $\mathbb Q$ of the numbers in the following collections: $1$, $\zeta_q(1)=L_1(1;q)$, $\zeta_{q^2}(1)$, and $1$, $\zeta_q(1)$, $\zeta_q(2)=L_2(1;q)$ for $q=1/p$, $p\in\mathbb Z\setminus\{0,\pm1\}$.