The goal of this study is to develop a distributed, optimized multi-agent system for information retrieval that is computationally accurate and efficient, as seen in the following image using the Sentiment140 dataset (1.6 million tweets) as the input dataset. A MapReduce framework is created to achieve the goal by first analyzing three significant aspects, as shown in the above image.
Using the Hessian Mutual Distributed Ant Optimization model, comparable user interest tweets are acquired during the Map phase. Using these findings, the second phase generates the combined vector, and the last step, the reduction phase, uses the Perron–Frobenius Eigen Vector Centrality model to produce accurate and dimensionality-reduced tweets. Here is a detailed explanation of the suggested approach, along with information on graph theory and the identified issue.
3.1. Graph Theory
Let graph ‘
’ represents a digraph, where ‘
’ represents the vertex set, ‘
’ represents the edge set, comprising of interaction links, ‘
’ corresponding to the associated adjacency matrix,
’ is denotes the probability, ‘H’ is Hessian matrix and ‘
’ is a corresponding weight. To be specific an edge ‘
’ denotes that agent ‘
’ can access the information of agent ‘
’ but not conversely. In addition, let ‘
’ be the matrix ‘
’ for corresponding ‘
’ row and ‘
’ column. Then, the adjacency matrix ‘
’ is written as given below.
where
and
—refers the Agents,
—refers the Edge set.
The digraph ‘’ is referred to as firmly associated if for any pair ‘’ and ‘’ in the graph, there is a path by following which vertex ‘’ can be reached by vertex ‘’. For any vertices set, ‘’, the distance ‘’, is referred to as the range of the shortest path from ‘’ to ‘’. To develop a multi-agent distributed system for social networks, the work proposed to provide each network centrality unit (i.e., eigen vector centrality) with a multi-agent (i.e., Twitter agent) responsible for the optimal operation of that unit. In digraph theory and analysis of social networks, network centrality refers to the most predominant vertices within a graph. In our work, this refers to the identification of the most influential tweets in a social network.
By utilizing vertex set ‘’ and edge set ‘’ to represent the agents and communication mediums, the above-bestowed graph symbols are utilized to detail the multi-agent distributed system for social networks. Since some mediums may not be utilized to send tweets at time ‘’, a different annotation ‘’ to express the communication between users during tweet at time ‘’ taking into consideration only the utilized mediums. Edge ‘’ is in ‘’, if agent ‘’ sends tweet to ‘’, at time ‘’, otherwise, ‘’.
3.3. Hessian Mutual Distributed Ant Optimization Model
Identifying the equivalent users’ tweets that connect two agents (i.e., Twitter agent) is the first step in the modeling of the proposed multi-agent-based distributed system.
This is performed in the proposed work in the Map Phase by applying Hessian Mutual Distributed Ant Optimization HM-DAO model.
Figure 2 shows a sample HM-DAO configuration for a partitioned social network map.
As illustrated in the above HM-DAO configuration, social network map contains, ‘’ users, ‘’ computers, ‘’ twitter agents, with users’ tweets represented in the form of a circle and agents denoted in the form of squares. A distributed model for a multi-agent system is designed using ant colony optimization with a category of time-changing cost function by considering the Hessian Matrix. This is due to the reason that the users’ tweet acquired as input by the multi-agent system changes or evolves over time and hence the ideal point of multi-agent would be changing over time.
Let us consider a function ‘
’ considering as input users’ tweets (i.e., simply tweets) procured by each agent as a vector ‘
’ and outputting a function ‘
’. With the assumption that all second partial derivatives of ‘
’ exist for a time-varying function (i.e., with users’ tweets evolving over time), the hessian matrix of overall tweets procured for each agent is mathematically expressed as given below,
where
—Hessian matrix,
—Second order partial derivatives of function ‘
’,
—Partial derivative of agent state of user
and
.
In this manner, from Equation (4), the time-changing users’ tweets, are procured by the multi-agent system in the form of hessian matrix ‘’. With the obtained hessian matrix of overall tweets procured for each agent, the distributed ants’ environment (i.e., the nodes of the graph representing the users’ tweets in the social network in our case) is designed as a set of interconnected Twitter agents.
In the proposed work, the Twitter agents (or agents) have their own action of control and determine in an independent manner to perform an action, interfaces with other agents’ serial passing of messages between agents assigned using the agent identifier ‘
’. The agent-acquired users’ tweets moving from user ‘
’ to user ‘
’ with probability ‘
’ for each hessian matrix ‘
’ is measured as given below.
where
—Hessian matrix,
—Input users,
—Amount of pheromone (agent acquired tweets) moving from user ‘
’ to user ‘
’,
—Weight inverse,
—Criterion to manage the impact of ‘
’ and ‘
’.
However, to process a huge volume of data (i.e., Big Data), better solutions are required to be manifested with more pheromones (agent-acquired tweets). Hence, at any time agent ‘
’ with agent identifier ‘
’ acquires a tweet ‘
’ of cost ‘
’ finer than the best-acquired tweet chunks, the agent will increase the pheromone strength on each edge of the tweet with a value ‘
’, that is equivalent to the characteristic of the solution. This is mathematically expressed as given below.
where
—Amount of pheromone moving from user ‘
’ to user ‘
’ at any time agent ‘
’,
—Cost inverse at any time agent ‘
’,
—Tweet at any time agent ‘
’.
When an agent completes a tour (or acquires all the users’ tweets collected at a particular time interval), it will uncover backwards its moves plotting the users on the way with pheromone (agent-acquired tweets). The update also considers pheromone evaporation. In our experiments, we used the mutual weights of each tweet. This is mathematically evaluated as given below.
From the above Equation (7), the weights of each tweet ‘
’ are obtained based on the number of times that tweet is found to the number of twitter API in which the tweets under consideration are found ‘
’, respectively. With the aid of ‘
’ and its corresponding weight ‘
’, similar user interests tweet ‘
’ are arrived at. The Algorithm 1 representation of the Hessian Mutual Distributed Optimization is given below.
Algorithm 1. Hessian Mutual Distributed Optimization. |
Input’
|
Output |
Step 1: Begin |
Step 2: For each Users ‘U’ with Tweets ‘’
|
Step 3: Obtain Hessian time-changing tweet function using (4)
|
Step 4: Evaluate probability factor for each obtained hessian matrix using (5)
|
Step 5: Obtain better solutions using (6)
|
Step 6: Evaluate mutual weight of each tweets using (7)
|
Step 7: Return (similar user interests tweet ‘’)
|
Step 8: End for |
Step 9: End |
As given in the above Hessian Mutual Distributed Optimization algorithm, for each user’s tweets obtained by the multi-agent (i.e., the Twitter agent), the objective here remains in obtaining the similar user interests tweets in a computationally efficient manner. This is performed in our work by applying the Hessian time-changing tweet function as the tweets evolved changes over time. Next, better solutions for each Twitter agent are arrived at by means of hessian distributed optimization model weight mutual weight. In this manner, similar user interest via a Twitter agent is obtained in a computationally efficient manner.
3.4. Perron–Frobenius Eigen Vector Centrality Model
With similar user interest tweets obtained via Twitter agent, dimensionality-reduced tweets are generated. These are generated by means of the Perron–Frobenius Eigen Vector Centrality (PF-EVC) model. The Perron–Frobenius Eigen Vector Centrality is an assessment of the impact of a user’s tweet on a social network. It allocates correlative scores to all users’ tweets in the social network on the basis of the hypothesis that relationships to high-scoring users’ tweets bestow more to the score of the users’ tweets than equivalent relationships to low-scoring users’ tweets. To obtain relevant tweets and at the same time to reduce the dimensionality of data (i.e., users’ tweets), in this work, the Perron–Frobenius Eigen Vector Centrality model is used. The flow diagram of the PF-EVC model is given below
Figure 3.
The elaborate description of the PF-EVC is given below. To measure the Forbenius Eigen Vector Centrality of a users’ tweet (or simply tweet), the significance of all other tweets that tweet ‘
’ is associated has to be evaluated. On the basis of this correlative significance, the Frobenius Eigen Vector Centrality of a tweet is calculated as given below. Let us assume the vector index ‘
’ and weight index ‘
’, the eigen vector significance is measured as given below.
where
—Eigen Vector Significance,
—User tweet,
—Weight,
—Vertices,
—Neighbor users similar interest tweet.
From the above Equation (8), the ‘
’ of each user’s similar interest tweet ‘
’ is arrived at based on each of the neighbor users’ similar interest tweet (i.e., ‘
’ to ‘
’) with corresponding to the weight and ‘vertices. Then, the eigen vector centrality score (i.e., dimensionality-reduced tweets) is measured as given below.
where
—Eigen vector centrality score,
—Constant value called the Perron–Frobenius value,
—Adjacency matrix.
From the above Equation (9), ‘
’ with vertex ‘
’ is linked to vertex ‘
’ for the corresponding adjacency matrix ‘
’, respectively. The Algorithm 2 representation of Perron–Frobenius Eigen Vector Centrality is given below.
Algorithm 2. Perron–Frobenius Eigen Vector Centrality. |
Input |
Output: Dimensionality reduced tweets |
Step 1: Begin |
Step 2: For each Users ‘’ with similar interest tweets ‘’
|
Step 3: Measure correlative significance using (8)
|
Step 4: Measure eigen vector centrality score using (9)
|
Step 5: Return dimensionality reduced tweets ()
|
Step 6: End for |
Step 7: End |
As given in the above Perron–Frobenius Eigen Vector Centrality algorithm, for each user with similar interests tweets provided as input, the objective here remains in obtaining the dimensionality reduced tweets for selecting their choices of interests for social networks have been designed. With this objective, two factors are concerned. They are measuring the correlative significance based on the Eigen Vector Centrality and eigen vector centrality score using Perron–Frobenius value. With these two factors, only the greatest eigen value results are acquired, therefore contributing to dimensionality reduced tweets and eliminating the lesser influence eigen values.