Estimates for the error of approximation of classes of differentiable functions by Faber–Schauder partial sums

In the metric of the space $\varphi(L)$ generated by a continuous even function $\varphi(x)$ increasing on $[0,\infty)$ such that $\varphi(0)=0$, $\lim_{x\to\infty}\varphi(x)=\infty$ one finds estimates of the error of approximation by partial sums of Faber–Schauder series in the function classes $C^1$ and $W^1H_\omega$, where $\omega(t)$ is a concave modulus of continuity.
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