find the number of ways of forming an executive committee of four in a social committee consisting of 15 members if a particular man must be in the committee.

The arrangements of lipids in the membrane makes the cell semi permeable .

Are you asking about a street map usage  if so here is your answer  a street map for a very limited area could simply be a bit map or a .jpg image.  but a more general map would probably store the streets as vectors.  but you shouldn't assume that there is one way to do it