In the field of science and technology, the graph theory has offered several approaches to articulate any situation or concept. The use of graph theory enables the users to understand and visualize the situations like COVID-19. Looking at this pandemic disease, its impact and the preventing measures, the graph theory would be the most appropriate way to exercise the graph models with theoretical as well as practical aspects to control this epidemic. In the context of COVID-19, this chapter defines the variable set, variable graphs, and their types considering the variations in the vertex sets and edge sets. The virus graph and their type are discussed in this chapter that states that the Virus graph type I and III are not so perilous for all living beings, but virus graph type III and IV are extremely hazardous for the harmony of the world. Initially, the COVID-19 was in Virus graph-I type, but presently it is in Virus graph-II type. Given different aspects for expansion of pandemic, this chapter presents growth types of virus graphs and their variation as 1-1, 1-P, and 1-all growth types. This chapter provide the number of infected people after 'n' number of days concerning different values of P and growth rates with I0 = 100. At the end of this chapter, the country-wise starting dates of stages of the virus graph-I and II are specified. The concept of cut sets is applicable for the prevention of COVID-19 and the whole world is using the same analogy.

No abstract

No abstract

Graph theory plays significant role in every field of science as well as technology. Every situation can be articulated in terms of suitable graphs by using various approaches of graph theory. Considering the recent pandemic in the world and the precautions taken for prevention of the COVID 19, it is the most appropriate way to exercise the graph models with theoretical as well as practical aspects to control this epidemic. This paper defines the variable set, variable graphs and their types with respect to variable vertex sets and variable edge sets. Depending upon the nature of the pandemic, there are four types of Virus graphs. Virus graph I and III are not so perilous for all living beings. Although, Virus graphs II and IV are extremely hazardous for the harmony of the world. In view of different aspects for expand of pandemic, growth types of virus graphs are divided in 1-1, 1-P and 1-all growth types. The COVID19 initially was in Virus graph-I type, but presently it is in Virus graph-II types. We present the table involving the number of infected people after n days with respect to different values of P and growth rates with I0 = 100. Moreover, the country wise starting dates of stages of the virus graph-I and II are specified. The concept of cut sets is applicable for prevention of COVID19 and the whole world is using the same analogy.

No abstract