web science-2019讨论区

Group 17: discussion about session 2

 
Picture of 鹏举 邢
Group 17: discussion about session 2
by 鹏举 邢 - Tuesday, 21 May 2019, 3:37 PM
 

The network is the foundation and important component of the World Wide Web.There are many networks around us, such as:transport networks, power networks.

Picture of Yijie Chen
Re: Group 17: discussion about session 2
by Yijie Chen - Wednesday, 22 May 2019, 8:58 AM
 

Yes, we are still in a large social network, and even say that the network is closely related to us everywhere.There are many kinds of networks, and the relationship between them is very complex, but it can be roughly divided into uniform structure and chaotic structure.

Picture of 祖昊 梅
回复: Group 17: discussion about session 2
by 祖昊 梅 - Wednesday, 22 May 2019, 9:09 AM
 

We can also analyze it in terms of nodes. For example, nodes can represent train stations, power stations,people.The edges between nodes represent their relationships.

Picture of 修权 丁
回复: Group 17: discussion about session 2
by 修权 丁 - Wednesday, 22 May 2019, 10:21 AM
 

That's right, and many networks conform to the theory called six degrees of separation.

Picture of 宇轩 路
回复: Group 17: discussion about session 2
by 宇轩 路 - Wednesday, 22 May 2019, 10:33 AM
 

So why the number is six, not five or seven, can it be solved out by a mathematical way?

Picture of 昂 曹
回复: Group 17: discussion about session 2
by 昂 曹 - Wednesday, 22 May 2019, 4:51 PM
 

I heard it's because an experiment. In the 1960s, Milgren, a social psychologist at Yale University, designed a chain letter experiment. He randomly sent a chain letter to 160 people living in Omaha, Nebraska, in which he placed the name of a Boston stockbroker and asked each recipient to send the letter to a friend who he thought was closer to the stockbroker. A friend will do the same when he receives the letter. Eventually, most of the letters arrived at the stockbroker after five or six steps.The concept of six-degree partition (also known as "six-degree space") comes from this. And many scientists have studied this theory and proved it to some extent.

Picture of Zixuan Xiao
Re: 回复: Group 17: discussion about session 2
by Zixuan Xiao - Wednesday, 22 May 2019, 6:26 PM
 

You have raised a very interesting question. Actually, the number is not 6, is 5.2. This is a social experiment done by Milgram (he was also famous for his Electric shock experiment), in his study, he asked some subjects to make a contact with a target person (most of the subjects have no direct connection with the target person), only through letters. Subjects first mailed to their acquaintances, then acquaintances mailed to their acquaintances...finally make a connection between target person. The results that the mean number of intermediaries between starters and targets is 5.2, and in follow experiments the mean number is between 4-7. So the reason way this theory is a "Six" Degrees of Separation theory was not due to six its own specialty, but because six is a representation of several special numbers.

Let me make some extensions. This social finding became a mathematical network model in 1998, this was a very famous model, which open a new stage to the complex network researches, it is called ‘small-world’ networks. If you are interesting, you can read that paper published on Science at 1998, see attachment. Milgram's paper is also attached.

Picture of 宇轩 路
回复: Group 17: discussion about session 2
by 宇轩 路 - Wednesday, 22 May 2019, 10:38 AM
 

Well, for the World Wide Web, the link between web pages are not a normal distribution. A great majority of pages have very few links. It is in line with my life experiences.

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回复: Group 17: discussion about session 2
by 昂 曹 - Wednesday, 22 May 2019, 4:44 PM
 

Yes,it is dominated by small number of powerful hubs.it is a principal known as preferential attachment.

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Re: 回复: Group 17: discussion about session 2
by Zixuan Xiao - Wednesday, 22 May 2019, 5:50 PM
 

Network analysis are very powerful. They are a very powerful tool for web Science and modeling and modeling and understanding how things are connected.

Picture of Yijie Chen
Re: 回复: Group 17: discussion about session 2
by Yijie Chen - Wednesday, 22 May 2019, 6:29 PM
 

But we must remember that networks are just an abstraction even if they are very useful one.

Picture of Zixuan Xiao
Re: Group 17: discussion about session 2
by Zixuan Xiao - Wednesday, 22 May 2019, 6:34 PM
 

I think it's an interesting topic who is the most powerful person in the network.

Picture of 昂 曹
回复: Re: Group 17: discussion about session 2
by 昂 曹 - Wednesday, 22 May 2019, 7:39 PM
 

Yes, and we can think about it in different ways.The simplest analysis is to simply count up the connections for each node.We can claim that the node with the highest degree is the on that is best positioned in the network.