On Estimates in $L_2(\mathbb{R})$ of Mean $\nu$-Widths of Classes of Functions Defined via the Generalized Modulus of Continuity of $\omega_{\mathcal{M}}$

For the classes of functions
$$W^r(\omega_{\mathcal{M}},\Phi):=\{f \in L^r_2(\mathbb{R}): \omega_{\mathcal{M}}(f^{(r)},t) \le \Phi(t) \ \forall\,t \in (0,\infty)\},$$
where $\Phi$ is a majorant and $r \in \mathbb{Z}_{+}$, lower and upper bounds for the Bernstein, Kolmogorov, and linear mean $\nu$-widths in the space $L_2(\mathbb{R})$ are obtained. A condition on the majorant $\Phi$ under which the exact values of these widths can be calculated is indicated. Several examples illustrating the results are given.