1. Researcher M.Sc. Mikko Vapa University of Jyväskylä
Power-law Networks InBCT 3.2 Peer-to-Peer communication Cheese Factory -project
Researcher M.Sc. Mikko Vapa University of Jyväskylä
Agora Center

2. Highway map
Flight map

3. Maps and their route distribution
Highway routes follow normal distribution:
But because of hubs like Helsinki flight routes have different characteristics. This structure is called power-law distribution:
γ = degree exponent
2002

4. Power-law structured network
Power-law network of 50 nodes
Nodes 1, 2, 3 and 4 are the most visible hubs
2002

5. History of Power-law Networks
Despite that power-law networks have been out there since life was born they were just recently discovered (in 1999 World Wide Web was found to be a power-law network)
In a short time many other network maps were found to follow power-law distribution:
Internet routers and cables
Social networks (only 6 hops between any people in the world)
Companies (Nokia as a hub with many small subcontractors)
Molecules and chemical reactions in living organisms (H2O, ATP, ADP and CO2 molecules as hubs)
Peer-to-peer networks (Gnutella diagnosed as the first one)
During years researchers came into a conclusion that this structure is universal and dominates all forms of life and organisation in complex systems and societies
2002

6. Characteristics of Power-law network
Fault-tolerant meaning that no matter how many nodes fail the network stays connected
Short network distance between any node in the network meaning that searching can be done efficiently
Still unclear:
How do these networks emerge?
research on evolution of networks is needed
What is the most efficient way to search these networks?
new search algorithms are needed
Reference: Barabási, A.-L., ”Linked – The New Science of Networks”, Perseus Publishing, 2002
2002
EUROOPAN UNIONI