In article <11*********************@d34g2000cwd.googlegroups. com>,

dhan <dh***********@gmail.comwrote:

>thanking you for given the good information in the graph but my

question is not only what is graph. my object why need or use to the

graph,

Examples:

- "directed graphs" (one that has "one way" links) can be used to

represent roadways, showing the distance between various points and

taking into account that some roads may be blocked (or only available

during certain times.) There are standard mathematical calculations

that can be used with such graphs in order to find the shortest

or fastest way to get from any given point to any other given point.

mapquest.com and googlemaps.com use these kinds of algorithms to

give road directions, and such things have even been put into

automobiles ("Navistar") so that you can get directions from where

you are to where you want to go. If the data is updated sufficiently

often, then these automobile navigation systems can even take into

account stalled cars and accidents and crowded roads in order to

recommend alternate routes that might be longer around but which

would be faster.

- Using calculations almost exactly the same as the above, you can

start with a terrain map and figure out the best way to get from

a starting point to every other point on the map. These calculations

would take into account that you can't walk through lakes, or that

walking through a swamp is slower than walking through a field,

or that a hill slows you down some and a mountain slows you down much

more (and might not be passable at all.) Knowing the fastest way

to get from place to place over terrain can be crucial to military

action (whether that be real life military action, or board games

simulating military action, simulated either for fun or for the

purpose of learning good military strategy.)

- "binary trees" and related structures such as "2-3 trees", are

really a form of graph; there are many many many uses for such graphs

- graphs can be important for operations or disaster planning, as they

can be used to figure out where the weak points are. For example, in

a city such a Stockholm, which has a series of linked islands, it can

be very important to know whether perhaps just having two bridges

damaged or inoperable (through flooding, repairs, iceing, traffic

accidents) would effectively isolate parts of the city from other parts.

Consider the building you live in: how many exits would have to be

blocked by smoke or fire for you to have no way to get out in case

of emergency? Ah, you missed the possibility that you were using the

basement bathroom and the only stairs to the main level were blocked...

- graphs can also be used in business planning and construction

planning, to figure out scheduling order, scheduling conflicts and to

figure out "critical points" that have to be completed in order to

advance the rest of the goals

- graphs can be used to assign students to classes and courses,

based upon the number of classes and the class sizes and the class

scheduling conflicts, and including the student preferences about which

courses they would prefer.

--

All is vanity. -- Ecclesiastes