【计】 acyclic digraph
naught; nonexistence; not; nothing; without; lack; zero
【医】 a-; leipo-; lipo-; non-
circle; enclose; fold; loop; mark with circle; pen; ring
【计】 ring up
【化】 circle; enclose; loop; ring
【医】 band; circle; circulus; helico-; ring
【计】 digraph; directed graph; oriented graph
【化】 digraph