 It is also possible to check whether a given directed graph is a DAG in linear time , either by attempting to find a topological ordering and then testing for each edge whether the resulting ordering is valid or alternatively , for some topological sorting algorithms , by verifying that the algorithm successfully orders all the vertices without meeting an error condition . 
 It <a href='drop_aux' title='1'><mark>is</mark></a>also possible to check whether a given directed graph is a DAG in linear time , either by attempting to find a topological ordering and then testing for each edge whether the resulting ordering <a href='drop_aux' title='2'><mark>is</mark></a>valid or alternatively , for some topological sorting algorithms , by verifying that the algorithm successfully <a href='uninflect' title='3'><mark>orders</mark></a> all the vertices without meeting an error condition . 
It also possible to check whether a given directed graph is a DAG in linear time , either by attempting to find a topological ordering and then testing fir each edge whether the resulting ordering valid or alternatively , fir sum topological sorting algorithms , by verifying dat the algorithm successfully order all the vertices without meeting an error condition .