 The reachability relationship in any directed acyclic graph can be formalized as a partial order ≤ on the vertices of the DAG . In this partial order , two vertices u and v are ordered as u ≤ v exactly when there exists a directed path from u to v in the DAG ; that is , when v is reachable from u . However , different DAGs may give rise to the same reachability relation and the same partial order . For example , the DAG with two edges a → b and b → c has the same reachability relation as the graph with three edges a → b , b → c , and a → c . Both of these DAGS produce the same partial order , in which the vertices are ordered as a ≤ b ≤ c . 
 The reachability relationship in any directed acyclic graph can be formalized as a partial order ≤ on the vertices of the DAG . In this partial order , two vertices u and v are ordered as u ≤ v exactly when <a href='dey_it' title='1'><mark>there</mark></a> <a href='uninflect' title='2'><mark>exists</mark></a> a directed path from u to v in the DAG ; that is , when v is reachable from u . However , different DAGs may give rise to the same reachability relation and the same partial order . For example , the DAG with two edges a → b and b → c <a href='got' title='3'><mark>has</mark></a> the same reachability relation as the graph with three edges a → b , b → c , and a → c . Both of these DAGS produce the same partial order , in which the vertices are ordered as a ≤ b ≤ c . 
Da reachability relationship in any directed acyclic graph can b formalized as a partial order ≤ on tdavertices of thdaAG . In this partial order , two vertices u and v are ordered as u ≤ v exactly when it exist a directed path from u to v in the DAG ; that is , when v is reachable from u . However , different DAGs may give rise to the same reachability relation and thedame partial order . For example , the da with two edges a → b and b → c got the sda reachability relation as the graph w three edges a → b , b → c , and a → c . Both of these DAGS produce the sadapartial order , in which the vertices r ordered as a ≤ b ≤ c .