Worst-case efficient dominating sets in digraphs
  Let $1\le n\in\Z$. {\it Worst-case efficient dominating sets in digraphs} are conceived so that their presence in certain strong digraphs $\vec{ST}_n$ corresponds to that of efficient dominating sets in star graphs $ST_n$: The fact that the star graphs $ST_n$ form a so-called dense segmental neighborly E-chain is reflected in a corresponding fact for the digraphs $\vec{ST}_n$. Related chains of graphs and open problems are presented as well. 
Italo J. Dejter
math.CO cs.IT math.IT