We show that for a sequence in a Banach space, the property of being stable under large perturbations characterizes the property of being equivalent to the unit vector basis of $l_1$. We show that a normalized unconditional basic sequence in $l_1$ that is semi-normalized in $l_\infty$ is equivalent to the standard unit vector basis of~$l_1$.
Minimality, homogeneity and topological 0-1 laws for subspaces of a Banach space
On quotients of Banach spaces having shrinking unconditional bases
An interplay between the weak form of Peano's theorem and structural aspects of Banach spaces
![QR code for arXiv:math/0010128 [math.FA]](http://oss.arxitics.com/images/favicon.svg)