an edge that is between a vertex and itself is a loop.
an edge that is between a vertex and itself is a?
loop
once a dummy initial vertex with an edge to every initial vertex and a dummy accepting vertex with an edge from every accepting vertex are added, checking if there is an accepting computation only requires to check if there is a path from the initial vertex to the accepting vertex, which is the reachability problem.





























a computation is said to be unambiguous if there exists at most one path from an initial vertex to an accepting vertex.





























a cycle in the graph corresponds to an infinite loop in the computation.





























section::::size of the graph.
configuration graph
the degree of a vertex, denoted 𝛿(v) in a graph is the number of edges incident to it. an isolated vertex is a vertex with degree zero; that is, a vertex that is not an endpoint of any edge (the example image illustrates one isolated vertex). a leaf vertex (also pendant vertex) is a vertex with degree one. in a directed graph, one can distinguish the outdegree (number of outgoing edges), denoted 𝛿(v), from the indegree (number of incoming edges), denoted 𝛿(v); a source vertex is a vertex with indegree zero, while a sink vertex is a vertex with outdegree zero. a simplicial vertex is one whose neighbors form a clique: every two neighbors are adjacent. a universal vertex is a vertex that is adjacent to every other vertex in the graph.
vertex (graph theory)