# 社交网络上的谣言传播

Rumor is an important form of social communications, and the spread of rumors plays a significant role in a variety of human affairs. There are two approaches to investigate the rumor spreading process: the microscopic models and the macroscopic models. The macroscopic models propose a macro view about this process are mainly based on the widely used Daley-Kendall and Maki-Thompson models. Particularly, we can view rumor spread as a stochastic process in social networks. While the microscopic models are more interested more on the micro interactions between individuals.

### 谣言传播模型Rumor Propagation Models

In the last few years, there has been a growing interest in rumor propagation in Online social networks problems where different approaches have been proposed to investigate it. By carefully scrutinizing the existing literature, we categorize the works into macroscopic and microscopic approaches.

### 宏观模型Macroscopic models

The first category is mainly based on the Epidemic models [1] where the pioneering research engaging rumor propagation under these models started during the 1960s.

### 传染病模型Epidemic models

A standard model of rumor spreading was introduced by Daley and Kendall,[1]. Assume there are N people in total. And those people in the network are categorized into three groups: ignorants, spreaders and stiflers, which are denoted as I, S, and R respectively hereinafter:

• I: people who are ignorant of the rumor;
• S: people who actively spread the rumor;
• R: people who have heard the rumor, but no longer are interested in spreading it.

• I: 无知者(ignorants)，对谣言一无所知的人;
• R: 谣言抑制者(stiflers)，听说过谣言但不再有兴趣散布谣言的人。

The rumor is propagated through the population by pair-wise contacts between spreaders and others in the population. Any spreader involved in a pair-wise meeting attempts to “infect” the other individual with the rumor. In the case this other individual is an ignorant, he or she becomes a spreader. In the other two cases, either one or both of those involved in the meeting learn that the rumor is known and decided not to tell the rumor anymore, thereby turning into stiflers.

One variant is the Maki-Thompson model[2] .In this model, rumor is spread by directed contacts of the spreaders with others in the population. Furthermore, when a spreader contacts another spreader only the initiating spreader becomes a stifler. Therefore, three types of interactions can happen with certain rates.

$\displaystyle{ \begin{matrix}{}\\ S+I\xrightarrow{\alpha}2S \\{}\end{matrix} }$

(1)

which says when a spreader meet an ignorant, the ignorant will become a spreader.
$\displaystyle{ \begin{matrix}{}\\ S+S\xrightarrow{\beta}S+R \\{}\end{matrix} }$

(2)

which says when two spreaders meet with each other, one of them will become a stifler.
$\displaystyle{ \begin{matrix}{}\\ S+R\xrightarrow{\beta}2R \\{}\end{matrix} }$

(3)

which says when a spreader meet a stifler, the spreader will lose the interest in spreading the rumor, so become a stifler.

1

({{{3}}})

$\displaystyle{ \begin{matrix}{}\\ S+S\xrightarrow{\beta}S+R \\{}\end{matrix} }$

(2)

$\displaystyle{ \begin{matrix}{}\\ S+R\xrightarrow{\beta}2R \\{}\end{matrix} }$

(3)

Of course we always have conservation of individuals:

$\displaystyle{ N=I+S+R }$

The change in each class in a small time interval is:

$\displaystyle{ \Delta S \approx - \Delta t \alpha IS/N }$
$\displaystyle{ \Delta I \approx \Delta t [{\alpha IS \over N} - {\beta I^2 \over N} - {\beta IR \over N}] }$
$\displaystyle{ \Delta R \approx \Delta t [{\beta I^2 \over N}+{\beta IR \over N}] }$

$\displaystyle{ \Delta S \approx - \Delta t \alpha IS/N }$
$\displaystyle{ \Delta I \approx \Delta t [{\alpha IS \over N} - {\beta I^2 \over N} - {\beta IR \over N}] }$
$\displaystyle{ \Delta R \approx \Delta t [{\beta I^2 \over N}+{\beta IR \over N}] }$

Since we know $\displaystyle{ S }$, $\displaystyle{ I }$ and $\displaystyle{ R }$ sum up to $\displaystyle{ N }$, we can reduce one equation from the above, which leads to a set of differential equations using relative variable $\displaystyle{ x=I/N }$ and $\displaystyle{ y=S/N }$ as follows

$\displaystyle{ {dx \over dt} = x \alpha y - \beta x^2 - \beta x(1-x-y) }$
$\displaystyle{ {dy \over dt} = - \alpha xy }$

which we can write

$\displaystyle{ {dx \over dt} = (\alpha + \beta)xy - \beta x }$
$\displaystyle{ {dy \over dt} = - \alpha xy }$

$\displaystyle{ {dx \over dt} = x \alpha y - \beta x^2 - \beta x(1-x-y) }$
$\displaystyle{ {dy \over dt} = - \alpha xy }$

$\displaystyle{ {dx \over dt} = (\alpha + \beta)xy - \beta x }$
$\displaystyle{ {dy \over dt} = - \alpha xy }$

Compared with the ordinary SIR model, we see that the only difference to the ordinary SIR model is that we have a factor $\displaystyle{ \alpha + \beta }$ in the first equation instead of just $\displaystyle{ \alpha }$. We immediately see that the ignorants can only decrease since $\displaystyle{ x,y\ge 0 }$ and $\displaystyle{ {dy \over dt}\le 0 }$. Also, if

$\displaystyle{ R_0={\alpha +\beta \over \beta} \gt 1 }$

which means

$\displaystyle{ {\alpha \over \beta}\gt 0 }$

the rumour model exhibits an “epidemic” even for arbitrarily small rate parameters.

$\displaystyle{ R_0={\alpha +\beta \over \beta} \gt 1 }$

$\displaystyle{ {\alpha \over \beta}\gt 0 }$

### 社会网络中的传染病模型Epidemic models in social network

We model the process introduced above on a network in discrete time, that is, we can model it as a DTMC. Say we have a network with N nodes, then we can define $\displaystyle{ X_i(t) }$ to be the state of node i at time t. Then $\displaystyle{ X(t) }$ is a stochastic process on $\displaystyle{ S=\{S,I,R\}^N }$. At a single moment, some node i and node j interact with each other, and then one of them will change its state.

Thus we define the function $\displaystyle{ f }$ so that for $\displaystyle{ x }$ in $\displaystyle{ S }$,$\displaystyle{ f(x,i,j) }$ is when the state of network is $\displaystyle{ x }$, node i and node j interact with each other, and one of them will change its state.

The transition matrix depends on the number of ties of node i and node j, as well as the state of node i and node j. For any $\displaystyle{ y=f(x,i,j) }$, we try to find $\displaystyle{ P(x,y) }$. If node i is in state I and node j is in state S, then $\displaystyle{ P(x,y)=\alpha A_{ji}/k_i }$; if node i is in state I and node j is in state I, then $\displaystyle{ P(x,y)=\beta A_{ji}/k_i }$; if node i is in state I and node j is in state R, then $\displaystyle{ P(x,y)=\beta A_{ji}/k_i }$. For all other $\displaystyle{ y }$, $\displaystyle{ P(x,y)=0 }$.

The procedure on a network is as follows[3] :

ordered list

1= We initial rumor to a single node $\displaystyle{ i }$;

2= We pick one of its neighbors as given by the adjacency matrix, so the probability we will pick node $\displaystyle{ j }$ is
$\displaystyle{ p_j={A_{ji} \over k_i} }$
where $\displaystyle{ A_{ji} }$ is from the adjacency matrix and $\displaystyle{ A_{ji}=1 }$ if there is a tie from $\displaystyle{ i }$ to $\displaystyle{ j }$, and $\displaystyle{ k_i= \textstyle \sum_{j=1}^N A_{ij} }$ is the degree for node $\displaystyle{ i }$;

3= Then have the choice:

ordered list

3.1= If node $\displaystyle{ j }$ is an ignorant, it becomes a spreader at a rate $\displaystyle{ \alpha }$;

3.2= If node $\displaystyle{ j }$ is a spreader or stifler, then node $\displaystyle{ i }$ becomes a stifler at a rate $\displaystyle{ \beta }$.

4= We pick another node who is a spreader at random, and repeat the process.

1= 我们把谣言初始化赋予给节点 $\displaystyle{ i }$;

2= 从临接矩阵（adjacency matrix）中，我们选择一个它的临近节点$\displaystyle{ j }$, 它成为谣言传播者的概率是

$\displaystyle{ p_j={A_{ji} \over k_i} }$

3= 然后选择:

3.1= 如果节点 $\displaystyle{ j }$ 是无知者，它成为一个传播者的速率是 $\displaystyle{ \alpha }$

3.2= 如果节点 $\displaystyle{ j }$ 是一个传播者或谣言抑制者, 那么节点$\displaystyle{ i }$ 成为一个谣言抑制者的速率是 $\displaystyle{ \beta }$

4= 我们随机选择一个是传播者的节点, 并重复这一过程。

### 小世界中的传染病模型Epidemic Models in Small-World Network

We would expect that this process spreads the rumor throughout a considerable fraction of the network. Note however that if we have a strong local clustering around a node, what can happen is that many nodes become spreaders and have neighbors who are spreaders. Then, every time we pick one of those, they will recover and can extinguish the rumor spread. On the other hand, if we have a network that is Small World, that is, a network in which the shortest path between two randomly chosen nodes is much smaller than that one would expect, we can expect the rumor spread far away.

Also we can compute the final number of people who once spread the news, this is given by
$\displaystyle{ r_\infty=1-e^{-({\alpha +\beta \over \beta})r_\infty} }$
In networks the process that does not have a threshold in a well mixed population, exhibits a clear cut phase-transition in small worlds. The following graph illustrates the asymptotic value of $\displaystyle{ r_\infty }$ as a function of the rewiring probability $\displaystyle{ p }$.

$\displaystyle{ r_\infty=1-e^{-({\alpha +\beta \over \beta})r_\infty} }$

### 微观模型Microscopic models

The microscopic approaches attracted more attention in the individual's interaction: "who influenced whom." The known models in this category are the information cascade and the linear threshold models[4], the energy model[5], HISB model [6] and Galam's Model[7].

### HISB模型 HISB model

The HISB model is a rumor propagation model that can reproduce a trend of this phenomenon and provide indicators to assess the impact of the rumor to effectively understand the diffusion process and reduce its influence. The variety that exists in human nature makes their decision-making ability pertaining to spreading information unpredictable, which is the primary challenge to model such a complex phenomenon.Hence, this model considers the impact of human individual and social behaviors in the spreading process of the rumors.

HISB模型是一个谣言传播模型，它可以再现这种现象的趋势，并提供指标评估谣言的影响，从而有效地了解其扩散过程并减少其影响。人性中存在的多样性，使得人们传播信息的决策能力不可预测，这是对这样一个复杂现象建模的主要挑战。因此，该模型考虑了人类个体行为和社会行为对谣言传播过程的影响。

The HISB model proposes an approach that is parallel to other models in the literature and concerned more with how individuals spread rumors. Therefore, it try to understand the behavior of individuals, as well as their social interactions in OSNs, and highlight their impact on the dissemination of rumors. Thus, the model, attempts to answer the following question: "When does an individual spread a rumor? When does an individual accept rumors? In which OSN does this individual spread the rumors?.

HISB模型提出了一种与文献中其他模型平行的方法，更关注个人如何传播谣言。因此，它试图了解个人的行为，以及他们在在线社交网络（OSN）的社会互动，并突显其对谣言传播的影响。该模型试图回答以下问题:“一个人什么时候散布谣言?一个人什么时候会接受谣言？这个人在哪个社交网站上散布谣言。”

First, it proposes a formulation of individual behavior towards a rumor analog to damped harmonic motion, which incorporates the opinions of individuals in the propagation process. Furthermore, it establishes rules of rumor transmission between individuals. As a result, it presents the HISB model propagation process, where new metrics are introduced to accurately assess the impact of a rumor spreading through OSNs.

### 参考文献References

1. Daley, D.J., and Kendal, D.G. 1965 Stochastic rumors, J. Inst. Maths Applics 1, p. 42.
2. Maki, D.P. 1973 Mathematical Models and Applications, With Emphasis on Social, Life, and Management Sciences, Prentice Hall.
3. Brockmann, D. 2011 Complex Networks and Systems, Lecture Notes, Northwestern University
4. [1] D. Kempe, J. Kleinberg, É. Tardos, Maximizing the spread of influence through a social network, Proc. Ninth ACM SIGKDD Int. Conf. Knowl. Discov. Data Min. - KDD ’03. (2003) 137. doi:10.1145/956755.956769.
5. S. Han, F. Zhuang, Q. He, Z. Shi, X. Ao, Energy model for rumor propagation on social networks, Phys. A Stat. Mech. Its Appl. 394 (2014) 99–109. doi:10.1016/j.physa.2013.10.003.
6. A.I.E. Hosni, K. Li, S. Ahmed, HISBmodel : A Rumor Diffusion Model Based on Human Individual and Social Behaviors in Online Social Networks, in: Springer, 2018..
7. S. Galam, Modelling rumors: The no plane Pentagon French hoax case, Phys. A Stat. Mech. Its Appl. 320 (2003) 571–580. doi:10.1016/S0378-4371(02)01582-0.

Category:Social networks

This page was moved from wikipedia:en:Rumor spread in social network. Its edit history can be viewed at 社交网络上的谣言传播/edithistory