Graph theory – In my definition, this image is a closed tour? If so, how can I list the vertices? In this image, who is $ v_1, v_2, … $?

In my definition, is this a closed walk? If so, how can I list the vertices? In this photo, who is $ v_1, v_2, … $?

Definition: A closed path in a graphic is defined as an ordered collection of vertices $ (v_1, v_2, …, v_n) $ such that $ v_i $ Y $ v_ {i + 1} $ they are neighbors for all $ 1 leq i leq n-1 $Y $ v_n $ Y $ v_1 $ are neighbors Note that the walk can visit the same vertex or cross the same edge on more than one occasion.enter the description of the image here