Table 1.

Table of notations.

Notation	Definition
$\mathbf{A}$	Matrix
${\parallel ·\parallel }_{2,1}$	${\mathcal{l}}_{2,1}$-norm
$\mathbf{X}$	Dataset
K	Number of participants
$N_c$	Number of classes
N	Number of samples
$d_k$	Data dimensionality at client k