Observe the matrix given below
The above Matrix shows all zero at diagonal.
Let me draw a graph for this ,
Assume that A, B and C are entities in database , Say Person entity.
A – Ram , B – Suma, C – Prema
Ram – Posted Hello …. Suma – Commented Idiot 🙂 … Ram – Replied You Idiot … Prema – commented See every one call you as idiot 🙂
It is not mandatory that only A has to comment B ! , Even B can comment A .
So the first graph shown is a directed graph and it is wrong , It should be undirected graph.
Now assume that how a facebook keeps track of connected friends ? Mutual Friends ? how big is the graph of facebook ?
The intention of this article is , to teach you guys how a Matrix concept is used to represent a graph, and how a graph theory is used in realtime to represent a social networking site like facebook.
Now understand why one should learn Graph Theory and Matrices
Let us have a look into facebook DB and Big data Total Monthly Active users – 1,310,000,000 Total Mobile users – 680,000,000 Every 20 minutes on Facebook Links shared – 1 million Friend Requests – 2 million Messages sent – 3 million http://www.statisticbrain.com/facebook-statistics/