Suppression-unconditional basic sequence
= Suppression-unconditional basic sequence
{title2=$\|\sum_{i\in A}a_ie_i\|\leq C\|\sum_i a_ie_i\|$}
A basic sequence is suppression-unconditional with constant $C$ if every coordinate deletion satisfies the displayed inequality. When $C=1$, deletion never increases the norm. Uniformly bounded finite-coordinate projections imply unconditional convergence of the basis expansions; for real scalars, the sign-change constant is at most $2C$.