Automorphism groups of Steiner triple systems

Abstract

If $V$ is a Steiner triple system then there is an integer $N_V$ such that$,$ for $u\ge N_V$ and $u\equiv 1$ or $3$ $($mod$\,6),$ there is a Steiner triple system $U$ on $u$ points having $V$ as an ${\rm Aut} U$-invariant subsystem on which ${\rm Aut} U$ induces ${\rm Aut} V$ and ${\rm Aut} U\cong{\rm Aut} V$