  Let $X$ be a Banach space and $\mathcal{K}$ be a compact subset in $X$. We
consider a greedy algorithm for finding an $n$-dimensional subspace $V_n\subset
X$ which can be used to approximate the elements of $\mathcal{K}$. We are
interested in how well the space $V_n$ approximates the elements of
$\mathcal{K}$. For this purpose we compare the performance of greedy algorithm
measured by $\sigma_n(\mathcal{K})_X:=\text{dist}(\mathcal{K},V_n)_X$ with the
Kolmogorov width $d_n(\mathcal{K})_X$ which is the best possible error one can
achieve when approximating $\mathcal{K}$ by $n$-dimensional subspaces. Various
results in this direction have been given, e.g., in Binev et al. (SIAM J. Math.
Anal. (2011)), DeVore et al. (Constr. Approx. (2013)) and Wojtaszczyk (J. Math.
Anal. Appl. (2015)). The purpose of the present paper is to continue this line.
We shall show that there exists a constant $C>0$ such that $$
\sigma_n(\mathcal{K})_X\leq C n^{-s+\mu}\big(\log(n+2)\big)^{\min(s,1/2)},
\quad \ n\geq 1\,, $$ if Kolmogorov widths $d_n(\mathcal{K})_X$ decay as
$n^{-s}$ and the Banach-Mazur distance between an arbitrary $n$-dimensional
subspace $V_n \subset X$ and $\ell_2^n$ satisfies $d(V_n,\ell_2^n)\leq C_1
n^\mu$. In particular, when some additional information about the set
$\mathcal{K}$ is given then there is no logarithmic factor in this estimate.
