Subcomplex with no missing shells
= Subcomplex with no missing shells
A <CW subcomplex> has no missing shells if a cell with a shell-length boundary arc contained in the <CW subcomplex> is itself contained in the <CW subcomplex>. For $C'(1/6)$ it suffices that every excluded cell have a complementary boundary arc of length at least half its perimeter with no edge in the <CW subcomplex>: an arc lying in the <CW subcomplex> then has length at most half and cannot be a shell's exterior arc.