def _check_restart_params(self, restart_strategy, min_beta, s_greedy,
                              xi_restart):
        r
        if restart_strategy is None:
            return True
        if self.mode != 'regular':
            raise ValueError('Restarting strategies can only be used with '
                             'regular mode.')
        greedy_params_check = (min_beta is None or s_greedy is None or
                               s_greedy <= 1)
        if restart_strategy == 'greedy' and greedy_params_check:
            raise ValueError('You need a min_beta and an s_greedy > 1 for '
                             'greedy restart.')
        if xi_restart is None or xi_restart >= 1:
            raise ValueError('You need a xi_restart < 1 for restart.')
        return True