复旦大学：《网络科学导论 Introduction to Network Science》教学课件_4- Small world model

Network science An English introductory course for undergraduate students Lecturer: Dr. Cong LI ee@ Fudan University Adaptive Networks and Control Lab

Network Science Lecturer: Dr. Cong LI EE @ Fudan University —— An English introductory course for undergraduate students Adaptive Networks and Control Lab

Attention How to find or deliver a message to one person in the world? Easy Difficult? The story starts from

Attention! • How to find or deliver a message to one person in the world? • Easy? • Difficult? • The story starts from …

Generally, one person has no specific physical definitions of his/her partner, So, the problem is relatiⅤ e easier 众里寻她千百度 蓦然回首 那人却在 灯火阑珊处 BE高阳L 月彩酌 唾一生情

众里寻她千百度 蓦然回首 那人却在 灯火阑珊处 Generally, one person has no specific physical definitions of his/her partner, so, the problem is relative easier…

If, the target is physical limited? Not to in love, but, for simplicity, just send a mail to one randomly pre-selected person (without address) from other 7 billion persons on the earth IVISON OIGLE How can you make it? MIISSIONE Mission impossible?

If, the target is physical limited? • Not to in love, but, for simplicity, just send a mail to one randomly pre-selected person (without address) from other 7 billion persons on the earth. • How can you make it? • Mission Impossible?

Mission impossible? Stanley Milgram, in 1967 announced the mission is not impossible with his real-data experiments in the USa Why does he want do finish the mission?

Mission Impossible？ Stanley Milgram, in 1967, announced the mission is not impossible with his real-data experiments in the USA. Why does he want do finish the mission？

Stanley milgram the harvard professor who in 1967 preformed a series of experiments How many acquaintances would it take to connect two randomly selected individuals in the USA? DISNEYLAND Milgram’ S Answer: IT'S J SMALL WORLD” 5.5(6)

How many acquaintances would it take to connect two randomly selected individuals in the USA? Milgram’s Answer: 5.5(6) Stanley Milgram the Harvard professor who in 1967 preformed a series of experiments:

Milgram's experiment in 1967 How to carry out 1. Who are the initial /start Participants (randomly chosen 2. Participants are told who is the target person 3b. If they do not know the 3a. If they know the target target person on a personal basis person on a personal basis, mail this folder to acquaintance mail this folder directly to who is more likely than you to him(or her) know the target person

Milgram’s experiment in 1967 How to carry out? 1. Who are the initial /start Participants？ （randomly chosen） 2. Participants are told who is the target person！ 3a. If they know the target person on a personal basis, mail this folder directly to him (or her). 3b. If they Do NOT know the target person on a personal basis, mail this folder to acquaintance who is more likely than you to know the target person

具理说现律的 密送车轻人 鸡毛信 Milgrams experiment in 1967 毛信 started from omaha and wichita Targets location: Sharon(Massachusetts); Boston Targets identity: wife of a divinity graduate student: stock broker Links: postcards and mails Supposed chain length: >100 (FBD) OMAHA 42/160 completed chains, MILGILAMS 300 0A CHMN LEYTERX average 5.5(312) ILLUSTRATE L DEGPeES SAUL WLLLD PEJBUEM

Milgram’s experiment in 1967 started from Omaha and Wichita • Targets location: Sharon (Massachusetts); Boston • Targets identity: wife of a divinity graduate student; stock broker • Links: postcards and mails • Supposed chain length: >100 (FBI) • 42/160 completed chains, average 5.5 (3~12)

Question If you are interested in finding such answers. how to design the experiment now?

Question • If you are interested in finding such answers, how to design the experiment now?

A 500th person to the riaht of A Your Friends Friends Friends Only have local information to reach ur Friends Friend the(global)target Your Friends Given the network is You reachable in a definite (not many) steps The shortest path

Only have local information to reach the (global) target! Given the network is reachable in a definite (not many) steps. The shortest path